First on Race Day or Found on Road Dead?

"I'm willing to bet that you have a pinched wire in the steering column," Steve McBride said, who happens to be the Department Head of High-Performance at Ohio Technical College.
"The issues with the dash going dead at times and all the warning lights coming on at the same time, along with the intermittent no-crank, all seem to point to the pinched wire in the column. I've seen enough of those," Steve said.
I kept that in mind as I started the Ford Quick Test. The first step was to perform a visual inspection. I checked for aftermarket accessories and performance modifications, such as a performance chip, performance exhaust, air filter and the like. Nothing was found. I logged into Ford's OASIS system and checked for TSBs and other documents. I checked the battery and charging system. I checked all fuses, oil and coolant level. These checks are all part of Ford's QT.
Next, I checked for KOEO, KOER and continuous memory codes. Ford states to check the circuit related DTCs first and look for common denominators, such as signal return, reference voltage, and power feeds. All the DTCs were U-codes. U0151, U0155, U0402, U0418 and U0452.
It was all related to High-Speed CAN. Looking at the wiring diagram, I noted all common connectors, splices and splice packs. I then started to map out the communication DTCs between the modules with the schematic, reducing my search area, and remembering what Steve McBride said, I checked the HS CAN wires that ran from the Steering Column Control Module. I didn't have to go anywhere else. There was a copper-to-iron condition with one of the pinched CAN wires.
I had to do a wire repair on CAN. The wires are twisted together to reduce radiated EMI and also to mitigate the effects of nearby EMI intrusion. Twisted wire is used with balanced signals and you have to determine the characteristic impedance (which can't be measured with an ohm meter).
With CAN, an ECU subtracts the negative signal from the positive one, meaning that any voltage components present in both signals will be eliminated. Such interesting topics, including simple calculations, are covered in Steve's high-performance classes. Thanks to Steve, I was able to repair this truck in a New York Minute. As Johnny Carson once said, a New York Minute is the interval between a Manhattan traffic light turning green and the driver behind you honking his horn. That's fast!





 

 

“It’s going to be something simple, I’m sure,” Walter said, regarding a 2009 Acadia with a steering problem. The Acadia has a variable effort steering system that controls the amount of effort to steer the Acadia with changes in lateral acceleration and wheel speed.

“We replaced the actuator already,” Walter said.

The actuator is in the steering rack and pinion, a simple pintle valve and electromagnetic coil. The EBCM controls the actuator from a range of about 0-to-1-amp. Amperage goes down as vehicle speed goes up.

“We replaced the EBCM and it didn’t make any difference. How much is all this gonna cost me?” Walter asked.

“More than a little, less than a lot,” I said.

The EBCM uses the steering wheel position sensor input to calculate lateral acceleration during hard maneuvers.

“We replaced the steering wheel position sensor,” Walter said. “There is also a Service Steering System warning message on the dash.”

I already did my preliminary checks prior to visiting Walter’s facility. He said an upgraded radio was installed, a factory install. “The problems started after the upgraded radio was installed,” Walter said.

There were no TSBs or PI documents, and I unplugged the cell phone charger. I verified the concern and checked all fuses.

“We checked all the fuses and they’re fine.”

“Well, I’m checking them again,” I replied.

I checked the terminals at the EBCM, inspecting them with my magnifier.

“We did all that,” he said.

“Good—and so am I,” I said.

I checked the EBCM ground. Walter shook his head. “We did all that, Bob—you don’t know what’s wrong, do you?”

“No, not yet,” I said. I began doing a thorough visual inspection, looking for anything unusual. Sometimes rodent intrusion takes a toll.

“You won’t find anything,” Walter said.

It was getting kind of irritating.

I plugged in my Tech 2 to check communication with the modules. The ECM, Headlamp Control Module, the Vehicle Communication Interface Module, the EBCM, the Fuel Pump Control Module, and the Rear Diff Clutch Control Module were all communicating. The ABS lamp and the Red Brake Warning Lamp were illuminated. Several history U-codes but two current DTC’s were stored.

DTC C0450 5A:  Steering Assist Control Solenoid Actuator Circuit plausibility failure, and DTC C0450 00:  Steering Assist Control Solenoid Actuator Circuit.

The EBCM controls power to the actuator through a high side driver. Walter checked it with a test light while commanding the actuator on and off, and the test light glows. But on the ground side, the test light did not illuminate.

“Maybe the new EBCM is bad,” Walter suggested.

“You can’t check the GFET with a test light,” I said. This is how you check it, according to the service manual:

1. Connect a DMM, set on the diode setting, between the low control circuit terminal 1 and ground.
2. Command the VES actuator to 0% with a scan tool. The DMM reading should be greater than 2.5 volts or display O.L.

⇒X	If less than the specified value, test the low control circuit for a short to voltage or a short to ground. If the circuit tests normal, replace the EBCM.

3. Command the VES actuator to 100% with a scan tool. The DMM reading should be less than 1 volt.

⇒X	If greater than the specified range, test the low control circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.

4. If all circuits test normal, test or replace the VES actuator.

 

We checked the GFET with my Fluke meter on diode test and it passed.

“So, we do have another bad EBCM,” Walter said. “I also checked the wires with an ohm meter and they were good. It must be a bad EBCM.”

I focused on the wires going to the EVO actuator. Using my load tester, I found that the ground side leading from the GFET in the EBCM could not support a load. Closer inspection revealed some broken strands under the insulation not far from the actuator.

This was a misleading one because the problem apparently occurred shortly after a new radio was installed. That was merely a coincidence in this case. As far as the U-codes, maybe they flagged when the radio was replaced and the dealership didn’t bother to clear them.

“That’s all it was—a broken ground wire? And you’re going to charge me for a broken wire?”

“No, Walter—I repaired the wire for free. I charged you for my diagnostic time. That’s all I ever charge for.”

Walter settled down after a bit. He apologized for acting like a typical customer.

 

 

Ghosts in the Wiring

“I didn’t believe in the paranormal before, but ever since purchasing this car, strange things have been happening,” the driver said, obviously not wanting to be identified. “My wife complained of hearing strange noises, like crumpling paper, coming from the back seat about a month ago.”

The 2016 Regal had been in the shop on numerous occasions for a myriad of electrical conditions and multiple components had been replaced. “The door locks would cycle at times, sometimes the car wouldn’t start, and sometimes the radio would decide to play on its own,” the owner said, as I looked at the repair orders. The radio was replaced, the human machine interface module and the body control module.

There were no bulletins or other documents relating to known problems. There were no modifications, no aftermarket equipment and no other work history prior to the dealer. I found a U0029 (MOST Bus Performance) DTC and a U0001 (High Speed CAN Malfunction).

“There were a bunch of other codes, but I cleared them before you got here,” Tim said. Unfortunately, he did not write them down.

I performed a visual inspection and checked the power distribution components—all were okay. When nothing obvious shows up, I look for the not-so-obvious. I broke out my inspection camera and inside the dash I spotted signs of rodent intrusion. Wires were chewed. Years ago, vehicles were made from metal, glass and plastic and 100% of it was made from petroleum. These days, with “green manufacturing,” cars are made from soy, peanut oil, rice husks and other tasty morsels for critters. In the early 1940s, Henry Ford experimented with making plastic parts for automobiles. These experiments resulted in what was described as a "plastic car made from soybeans." Could you imagine how many toothsome rodents would have loved this car?

After we would perform a series of wire repairs, I suggested that the owner authorize wrapping the wires with rodent-proof tape, treated with capsaicin. Sprinkling crystallized fox or coyote urine around the tires also helps. I also found the source of the noise of crumpling paper: I found an active mouse nest under the rear seat. I carried the critters out to the woods so that they could live out their lives away from human intrusion.

We still had the window and headlamp issue. I noticed that the BCM was getting a request to turn those systems on—but from where? I used my scope to look at the GMLAN data stream and saw minor distortion, but when I decoded the CAN bus, I saw Error frames. Decoding is a good, quick indicator that CAN frames are being transferred between ECUs on the CAN Bus.

If you know the CAN database spec of your vehicle, it will be possible to ascertain which ID belongs to which ECU. There are several ways to ascertain this information The IDs and Data are normally shown in Hexadecimal, which is standard in the digital communications industry, however it is possible to display in Decimal if you wish. Decoding a data bus can be useful for seeing instability by sensing Error Frames. I spotted a problem that at 59.87 seconds after start of collection, Error frames started to occur. In fact, when I got the CAN database for the car, I saw that the coded hex was being misinterpreted by the gateway module as commands to illuminate the headlights and lower the driver window!

The “bad” code was sourced from the EBCM. The noise being put on the CAN bus from the EBCM was causing the issue. Remember the original complaint? It happened with the Power Mode Master (BCM) supposedly powering down. Some of the wiring damage caused the communications enable circuit to trigger the BCM. Terminal fretting at the EBCM connector caused Error Frames to appear on the decoded can bus. Multiple issues made this one a very difficult one to resolve.

“Now,” the driver said, “What about those shadows my wife seems to see at times in the car? Do I need to see someone to exorcise demons from the car?”

“Maybe,” I said, laughing, “Or maybe infrasound is the culprit.”

I experienced the negative effects of infrasound in a hotel room once. I just didn’t like the room for some reason and thought I saw odd shapes. It was due to the blower motor in the kitchenette causing the issue. I kept it on all night to act as a sound machine.

If infrasound hits at just the right strength and frequency, it can resonate with human eyes, causing them to vibrate. This can lead to distorted vision and the possibility of “ghost” sightings. Or, at least, what some would call ghost sightings. Infrasound may also cause a person to “feel” that there’s an entity in the room or vehicle with him or her, accompanied by that aforementioned sense of dread.

I hoped you enjoyed this “ghostly” challenge.

A Matter of Harmonics?

“We can’t visualize vibrations, but we tend to experience the effects of vibration, kind of like electricity,” Linda said. The shop had a high-tech vibration analyzer, embedded with a tri-axial accelerometer and laser tachometer.

“I get into vibration diagnostics because we see plenty of souped-up Duramax trucks down here,” She said.

I knew what she meant. Combustion puts such a forceful load on the crankshaft, it actually elastically deforms each time combustion occurs; fortunately, it fully recovers. An 8-cylinder deforms at least four times per rotation.

“Combustion puts a huge amount of force on each crank web, twisting the metal ahead of itself,” she said.

“Right,” I said, “and then it snaps back and creates harmonic frequencies that travel back and forth through the crankshaft. Normally, the harmonics are controlled so they have negligible effect on the main bearings because they work within a defined range of harmonics,” I said.

“Yes, but I’ve seen modified Duramax-equipped trucks where the harmonics affect the bearings and other parts big-time,” Linda said.

She was right because as the frequencies got closer to the natural frequencies of the components, wear increases tremendously due to uncontrolled oscillations.

“So many times the elastomeric damper can’t handle the modifications,” she said.

It wasn’t the case with the 6.2l engine we were working on. I studied the vibration. With the tri-axis sensor in the analyzer we were using (Fluke), my measuring point was in the seat track. This was a rough idle in drive we were dealing with.

Linda and Jeff explained that it was hard to duplicate the vibration. “Most rough idle in drive concerns are temperature dependent, and can be difficult to re-create at times,” I said. With A/C On, I performed several short heavy launch events from stop to stop to bring the temperatures back up while trying to re-create the rough idle vibration in drive with the meter’s sensor placed on inboard seat track in horizontal and vertical axis. It was picking up an E1.5 disturbance.

E1 is a first order engine vibration, simply engine speed, expressed in Hz (E1 x 60 = RPM). E1 vibrations can be accredited to parts related to engine speed such as flywheel and pulleys. High vibration levels detected at E0.5 can be related to half engine speed components, such as camshafts and associated auxiliaries. Usually, E2, a second order engine vibration happens at twice engine speed and will be the highest level of vibration (for a 4-cylinder engine) given we have two combustion events for every revolution of the crankshaft (two shocks applied to the crank), generating a characteristic high E2.  E2 vibration levels can be attributed to combustion events or components rotating at twice engine speed. On an 8 cylinder engine, E4 would be highest.  Ours was an E1.5, and with the vibration duplicated, at the inboard forward seat track location, it measured approximately 6.5 mg. In other words, we were looking at units of g (acceleration due to gravity)—specifically, milli-g. 
“I know,” Linda said, “I stress how important math is when it comes to diagnosis.”
Linda did not overlook the basic inspection, which was great. And she didn’t mind when I checked everything myself.  Engine oil and coolant level were confirmed correct; whilst hoses, brackets, harness routing and engine mounts were all checked for security, interference or fouling with the chassis.

 

 She did all these things but understood that I had to do them myself—for my own peace of mind. 
The shop tried to resettle the engine mounts but it didn’t affect the vibration. It has been my experience that oftentimes, an idle vibration caused by ground-out within an engine mount can turned off/on with a single bolt location – shimming that bolt location may greatly cut back the vibration. In some cases, a combination of bolt location shimming may be needed.
We managed to get it down to 2.6 mg, using mild steel spacer washers, and then road-tested the vehicle. The customer was satisfied.
Linda wasn’t aware of GM PI documents, and I showed the one we worked off of.

“I learned some things from you today, RJ. Thank you so much.”

Western Star

The 2012 Western Star 4900 Series with a Detroit Diesel Series 60 originally had a SPN 524/FMI 9 DTC stored, indicating a J1939 ETC2 Message Missing. The technicians working on this truck checked for proper CPC configuration, ultimately replacing the CPC, because it failed to download MCM static fault data. After that, an SPN 630/FMI 14 Code flagged.

This code indicated that the CPC failed to download MCM static fault data and the repair is to reprogram the CPC with the latest software release. “After we did that, we ended up with an inconsistent static fault code data, reported by the MCM,” a very frustrated Dave Gordon, the technician, said. “I reprogrammed the MCM with the latest software,” he said. It was after that, the SPN 625 FMI 9 code set—abnormal data update rate.

When I got to the shop, it was in a pole barn, well-equipped and well-lit. I performed all the basic checks: battery connections and battery state of charge; fuses, grounds—I found a bad ground at the CPC. Once we eliminated the bad ground, I took out my ancient AM pocket radio. The shop was filled with interference. I once found interference coming from the rain gutters of an old barn. The farmer used a ladder to get up to the loft, and when he grabbed the rain gutter for support, he screamed from an electric shock. The interference on my AM radio stopped. He came down the ladder, still shaking, and asked me if it could be connected to a problem he was having when touching the metal sink in the barn or the refrigerator. It was.

Getting back to the pole barn/truck shop: Electromagnetic Interference is caused by one device inducing voltage (generating a discrete voltage without a direct electrical connection) within a second component.  Induced voltage occurs when devices are not properly shielded, are laid out improperly (e.g. coiled around objects or run parallel for the entire distance), use high frequency AC voltage, or are grounded improperly.

His shop lights used electronic ballasts.  Because ballasts typically generate a humming or buzzing noise – electronic ballasts are quieter than traditional magnetic ballasts, but the hum still exists – remotely mounted ballasts are sometimes preferred, which is what Allman had in his shop. Remotely installed electronic ballasts generate substantial amounts of EMI due to their higher operating frequencies (magnetic ballasts operate at 60 Hz while electronic ballasts are typically operated at 20-60 KHz, that’s 50 to 200 times greater). 

 If the connection cables are unshielded, the high frequency will convert the cables into a powerful antenna, creating an electromagnetic field that can affect radios, Wi-Fi connections, and cell signals.  In a fluorescent system, the fluorescent lamp itself is capable of radiating electromagnetic waves at frequencies of 10 KHz to 100 MHz depending on the electronic ballast connected to it.

Allman’s top technician, Dave, was attempting to program the truck’s ECU’s in the presence of all that EMI.

“So, how can you eliminate EMI?” Allman asked.

“Ensuring proper ground connections for all electrical devices will shunt high frequency interference to an earth ground or common, for starters,” I said.  If grounding is not done properly, cables, grounds, or electrical equipment can act as a very powerful antenna, radiating out a strong EM field.  “Grounding the fixture and ballast to a common earth ground will help prevent this from occurring.”

“We do a lot of programming,” Dave said.

“Cable runs should be placed in metal conduits, and fluorescent or HID lights can be housed in luminaires with copper mesh or conductive glass to shield against EMI generated by the cables or lamps.”

I also mentioned that all exposed conductors should be shielded.  The conductive material of the shielding will absorb the EM field and prevent radiated or conducted EMI.

Allman vowed to get the EMI down to manageable levels in his shop. With the Western Star’s ECUs properly programmed (without interference), the problems were resolved.  

Of Corvette's and Kenworths

"I've tried everything on this Corvette and I can't get the AC compressor to turn on. It had a bad programmer, so I put another one in. Then it had a bad pressure switch that caused the ECM to set a code 66. I cleared the code but the compressor still won't turn on. The HVAC programmer was $780 and I think it is defective, but I don't want to get another and find out that something else is the culprit."
Max is a good technician. He graduated with a technical degree in both auto and diesel technology and is willing to learn. Some of the older technicians, just like instructors, don't like change. Some--not all--are unwilling to get out of their comfort zones and in this business, that's a no-no. An instructor owes it to the students to keep current. Students are reflections of their instructors.
The HVAC programmer is a rebuilt part. It was an R-12 system I had a suspicion what it was. I pressed the fan up & fan down buttons simultaneously until-00 appeared on the HVAC display. I was now in diagnostic mode. Once in diagnostic mode, you can use the fan up & down buttons to scroll through the PID list. To view the value at the PID location, you press the AUTO fan button. I went to PID position 00: System Faults. I found )), which indicated no codes. Then I went to PID position 09: A/C System Mode. It was 01, which meant MAX A/C. The command was there. I moved to PID 11: Program Number, which represents a heating or cooling command. The programmer was commanding 00, a command for FULL COLD. I moved to PID 34: TEMP DOOR POSITION REQUESTED. It was at -155, which means when you see a minus sign at the value, you add 100. So, -155 was 255, which was FULL COLD.
Everything looked good. I remembered the hidden programmer code:48. When I taught HVAC controls in another lifetime, I called Code 48 the "Claude Rains" Code. the young technician didn't know who Claude Rains was.
"He played the invisible man in the movie back in 1933," I said. "It was a classic movie."
"Oh," the young technician said. It was way before his time.
I plugged the Tech 1 scan tool into the data link connector. First, I went to PID 00 and used the clear codes command on the HVAC head. Then I used the Tech 1 to clear ECM codes. Then I turned the ignition key off, took the Tech 1 off the data link connector, started the Corvette, and the compressor energized.
"How did you do that?" The wide-eyed technician asked.
"With experience," I said. "The code 48 was intentionally masked from the programmer's data list, but if it set, it sent a signal over the UART bus to the PCM to disable the compressor. Code 48 was identified as a LONG TERM FREON LOSS code."
"But I disconnected the battery. Wouldn't that have cleared the hidden code?" The technician asked.
"Sometimes, but not always," I said.
That was an easy one, but only because I learned the hard way on that one, all those years ago. We learn good lessons from our mistakes. We have to--so history doesn't repeat itself.
Onward to the Kenworth in my next post.
 

Tools of the Trade

Like every good technician, I have an electrical tool kit consisting of wire and terminal repair tools and soldering equipment. I also keep a stock of other materials, such as:

Stabilant 22:
This material is electrically active and stays resident within a contact pair, enhancing conductivity without leakage between nearby contacts. It's initially non-conductive, amorphous that becomes conductive when exposed to an electric field.

Rodent-Deterrent Tape:
This tape is treated with capsaicin to protect those wires with soy-based coating.

Liquid Metal Defogger Grid Repair:
Great for a variety of repairs.

Bare Conductive Electric Paint:
Like any other water-based paint except that it is conductive. I also have a conductive paint pen.

Nyogel 760G:
A silica-thickened, synthetic hydrocarbon grease to protect electrical contacts.

Silver Conductive Glue Paste:
Cures at room temperature and air dries.

Nickel-Copper Cobalt Tape:
Great RF shielding--70 dB @ 1 MHz and 100 dB at 1 GHz.

The 2016 Impala that I worked on had intermittently activated the SERVICE STABILITRAC warning on the dash and the sound of "electrical arcing" under the hood. My homemade, electronic electroscope detected
a spark from the inside hub to the outside ring on the harmonic balancer.

 

Measuring the resistance from the center of the hub to the outside ring of the harmonic balancer, I found about 763 K Ohms. I cleaned the harmonic balancer off with brake cleaner. Next, I used my liquid metal defogger grid material, applying it from the center hub to the outer ring on the balancer across the rubber to control the resistance. I told Samuel it is a temporary repair. The intermittent P0300 and STABILITRAK message was due to terminal fretting at the EBCM connector, terminals #23 and #24. My 40x illuminated loupe comes in handy for close inspection. A loose ECM ground caused the misfire at times--the P0300.

 

The problems with the Kenworth were resolved. The Service Lamp was flashing and there were transmission issues on the UltraShift transmission controlled by the TECU. The culprit was a corroded power supply to the TECU. The shop never suspected this because the wiring had been replaced before. But the root cause? I spotted the dirty powder on and near the wiring with my UV light (just another use for it). That was caused by nitric acid formed in the presence of moisture in the air. So, where did the nitric acid come from? It was caused by the ionization of nitrogen in the air, and that was caused by an intense electric field.

This diesel had some add-in inverters, causing nearby corona discharge, due to the close proximity of the wiring. Corona eventually causes punctures and carbon tracking. Whenever I see wiring in close proximity of other wiring, especially from an upfitter, I use my UV light to look for the residue.

A technician has to have good detective skills and be persistent. Had I replaced the power wire to the TECU, it would have failed because I would have treated the symptom, not the disease.

 

 

Electronic Heartbeat?

“It’s a 2016 International and it was parked out back for the weekend when a storm blew in,” Ketchum Jessup said as we stood by the truck. “I was havin’ me a cup of coffee, watching the storm, when a bolt of lightning zapped my truck. Struck the mirror on the driver’s side and blew the glass out,” he said, gnawing on a plug of tobacco. “After that, the truck wouldn’t even crank over.”

I looked at the documentation of other repairs. Every module on the J1939 data link had been replaced: the ABS ECU, Auxiliary Gauge Switch Pack ECU, the Body Controller, the ECM, the Electronic Gauge Cluster and the Pyrometer Ammeter Module. On the second visit to the shop, the Body controller, the terminating resistors and the J1708 data link had been replaced.

“It ran for a little while and then the Engine Stop warning turned on,” Ketchum said. “So I had a mobile repair truck come out.”

I saw that the Body Controller was replaced again, Ignition 1 relay and the Auxiliary Power relay. The BC supplies ground to the auxiliary power relay when the theft deterrent is active. Then the key is ON, the auxiliary relay is energized and the relay opens. When the relay opens it allows power to be fed to the Ignition Relay 1, the Crank Inhibit relay and the ECM. If the auxiliary power relay is energized, the vehicle won’t run.

“Now the gauges tick-tock as if they were on a clock or heartbeat or something when the key shuts off. Sometimes it starts, sometimes it doesn’t,” he said.

I checked for recalls, campaigns, safety-related reports and the like, but nothing came up during my research. I checked connections at the battery as a standard procedure. I checked all the fuses.

“Those are all basic checks,” Ketchum said.

“Exactly,” I responded. I used my inspection camera mad carefully checked all ECU connections, including the door pods. I visually inspected all ECU grounds. I was going over all worked performed by the other shops. You have to. The one thing that you fail to check will be the thing that gets you.

When I decided to check the terminating resistors, that’s when my ohmmeter readings were all over the place, as if I had current flow after everything powered down. I disconnected the battery and checked the terminating resistors. Individually, they measured 120Ω, which was good. But when I checked the J1939 backbone, my ohmmeter indicated OL.

 I reconnected the battery and started the truck. It ran fine for a few minutes and then the Engine Stop light appeared. I turned the key off and the gauges would jump periodically. I disconnected the battery and measured the resistance of the J1939 backbone again. Again it returned OL. Was the data bus open?

I manually ranged my digital meter to the 4KΩ scale. I measured the bus again and the resistance slowly climbed until it returned OL on the display. I reversed the meter leads at the diagnostic link connector, and the reading on the ohmmeter red a negative resistance, counting down to 0.00Ω. It reversed polarity and counted up again, until reaching OL. Now I knew what was happening.

My meter’s 9V battery was charging a capacitor somewhere on the circuit. When I reversed the lead connections, the capacitor discharged and then charged up again. Once the voltage reached the same value on each side of the dielectric, the capacitor was fully charged. The meter displayed OL. I decided to unplug each ECU, one at a time. I was also cross-checking each number. The fourth ECU I disconnected caused the odd reading stop.

Modern heavy-duty trucks can be described as rolling computer networks with seemingly endless possibilities for data collection and transmission. Many different devices found on trucks have the ability of collecting and storing this data when an event occurs. These devices are collectively referred to as Heavy Vehicle Event Data Recorders (HVEDRs). In most cases, however, an HVEDR is not a device but a software application added to an existing device that has an original purpose other than collecting and storing incident data.

Data collected and stored by HVEDRs can be useful when analyzing a truck crash. The most useful data comes from trip/event data recorders on engine Electronic Control Modules (ECMs) and wireless fleet management systems (a.k.a. tracking/ communication systems, mobile resource management systems, and telematics systems). These systems can record vehicle speed, brake usage, vehicle-use histograms, vehicle position history, active and historic diagnostic trouble codes, and more. An endless number of devices used on trucks that have a HVEDR function and no two devices record the same data. Therefore, an HVEDR is like a Christmas present where you really don't know what you're going to get until you open it. You may think you know what is in the box and sometimes you are right but often it is a surprise.

This truck went to a bodybuilder at some point. The ECU was added that acted as a dedicated HVEDR. It must have contained a capacitor that charged and discharged. I opened the ECU. I found a choke that was charging a capacitor due to a bad conductive trace so I removed the cap, repaired the trace, installed a new cap, and checked it again. The capacitor was now functioning as designed.

Ketchum held the cap in his hand. That little thing called all this grief?”

“To you and me both,” I said.

I'm pointing to the cap.

 

Alien Makes and Models

“This one is serious, RJ,” the owner of a 2014 Kenworth said. “The EGR was non-functional, no DEF injection, reduced engine torque along with the MIL and STOP ENGINE light. Where do you start?”

The truck was a 2014 Kenworth, W900 Cummins ISX 15 CM 2350 truck. This one had a fault code 175 SPN 3464 FMI 3. The code indicated that the signal coming out of the throttle actuator is high. Considering that the throttle actuator was replaced three times, I strongly suspected it wasn’t the fault. I checked the terminals at the actuator and the ECM with my 40x magnifier, 25mm.—great for spotting terminal fretting.

 

We started by verifying the concern, followed by a thorough visual inspection. Research revealed no bulletins, although the Kenworth had a work history. The ECM was replaced and programmed. The throttle actuator was replaced three times, and a terminating resistor was replaced. I decided to decode the CAN bus packets, although I strongly suspected where the problem was—at the terminator that was replaced. I wanted to see how the data packets looked.

“What are we looking at? T.D. asked.”

“It is a Stuff Error, T.D. There is an issue with the terminating resistor that they replaced.”

This bit stuffing scheme is used to guarantee enough edges in the bit stream to maintain synchronization within a frame. If a listening device detects 6 bits of the same value, then it must have been the case that synchronization was lost and what was received was NOT what was sent! This is precisely what can happen with improper termination. Some bits in the frame are transmitted and received correctly, but the entire frame (and the integrity of all the bits in that frame) is not maintained and received at the listening CAN interface. 

Whoever worked on it before disconnected a 120Ω resistor, removed the other one and added two 120Ω resistors in series at one end. I didn’t know why. We repaired that issue.

Someone replaced the throttle actuator three times for a reason. My oscilloscope revealed AC noise to the neighborhood of 700 mV and that is a huge neighborhood.  The ECM was sending a regulated voltage signal out—dirty with AC noise of about 650 mV AC P-P. It was time to check the power feeds going into the ECM. Bingo!  The ECM power feed had about 500 mV AC ripple (the battery acts as a dampener, smoothing out AC current so a bad battery can cause strange symptoms in a vehicle). I had that condition on an Impala once. I checked the alternator with my scope: 1.2 volts AC!

Finally, the ECM ground had excessive voltage drop. After all the repairs, the Kenworth ran great. T.D. was happy to get it back on the road.

“Sorry you didn’t see any green aliens when you were here,” T.D. laughed.

“Did you ever see a UFO, T.D.?”

“No, but others around here have. There has been reports of saucers, cigar-shaped UFO, triangle-shaped, diamond-shaped and round ones,” He said. “We have a fair share of them.”

“You know what has always bothered me about the different shapes? I’ve always wondered if aliens have a choice of buying different models,” I said.

“What do you mean, RJ?”

“Well, we can buy an SUV, or a compact, or a sports car—and we can buy a Ford, Chrysler or GM; or imports. Judging by all the different UFOs, I just assumed that the aliens have choices of what to fly to our planet, T.D.”

He just shook his head.

Of Terminators and Characteristic Impedance

“Terrible what’s going on in this country,” Dan said, watching as I worked, tracing the data bus wires. “We’re proud of our heritage and now folks are taking it away from us,” he said as I worked. His truck had a DTC 148309, kept going into regeneration and he had it in to three different shops that replaced the complete aftertreatment system, including the doser valve three times.

“What do you think about all this stuff going on, Bob?”

“Actually, Dan, your truck is currently consuming whatever brain power I have at the moment,” I said.

He nodded. “I asked the technician working on it the last time to explain the J1939 data bus, but he wasn’t very clear.”

“The J1939 multiplexed chassis uses twisted-pair wiring, twisted to prevent the data backbone from acting as a radio antenna. The wires twist a through a full cycle once per centimeter on the backbone—2-1/2 times per inch,” I said.

My hand was getting cut up from the tight places I was going into.

“Those terminating resistors—they’re for signal noise, right?” Dan asked. “And the technician said they need to be 120 ohms, right?”

I checked V-CAN, E-CAN, D-CAN and A-CAN terminating resistance. The resistors each came in at 120-ohms.

“The truck J1939 data bus has a characteristic impedance of 120-ohms, but don’t confuse this with terminating resistors used at the end of the data backbone, Dan.”

“What is characteristic impedance, Bob?”

“It is just a factor of how a conductor appears to a high-frequency signal, regardless of length. You can’t measure it with a meter.”

Andrea, Dan’s wife, brought us some homemade lemonade. I loved her deep-southern accent. “Y’all thirsty?”

I thanked her and she noticed my bloody hand. “Y’all get into a cat fight?”

“No, just Dan’s truck,” I said.

Andrea offered to take care of the scrapes but I refused, saying that I was planning on getting a few more. She shook her head and went back towards the house.

“The terminating resistors also provide a low-resistive pathway for current flow between CAN H and CAN L. The capacitance can discharge and cancel rapidly,” I explained. “Of course, the length of time for a capacitor to drain is proportional to the resistance of the conductor it is discharging through. If capacitance can’t rapidly discharge when a component is trying to transmit at a low level, then the voltage differential between CAN H and CAN L stays high and that can shut down the data bus.”

“The truck has been stalling at times,” Dan said. “I had to disconnect the battery a couple of times to get it started.”

I scraped my hand up again, getting at the hidden wires while Dan held the light. “How do they come up with this impedance?” He asked.

“They do it by maintaining the dielectric constant, or wire insulation, and keeping the actual physical space between the two conductive wires constant by having a consistent twist pattern. Twist pattern is very important,” I said.

Then I found it. “Here is the problem.” I said. Someone repaired the CAN bus.”

“I could have told you that,” Dan said, “The dealer technician did it. He found some rubbed-through wire.”

“Yeah, but substituting ordinary wire for J1939 cables is a no-no because the dielectric properties of the insulation should be constant. You can corrupt communications on the bus by altering the impedance.”

“Corrupt? How, Bob?”

“Because the amount of time needed for every signal pulse pumped down the bus to neutralize increases; now the reflected signals scramble the data bus,” I said. I repaired the wiring, fired up the rig, and checked the data bus and all was well.

“I think we have it licked, Dan,” I said. Everything looked good.

We had great conversation later on over lemonade on the porch while Andrea insisted of doctoring up my hand. We talked about the protests and expressed feelings, but the world is tainted enough without letting it spill into my blog or Facebook.

Dan and Andrea are great people. I wish the world had more like them.  

Bearings and thrust washers destroyed by electricity?

A great friend of mine, Phil, reminded me of those golden years of the HydraMatic 350 transmission, used from about 1969 through 1984. It was typically paired with small block V6 and V8 engines. Although it was destined to become one of the greatest automatic transmissions ever built, we were having issues with the 350’s burning up back in the day.

I recall the first one I ever disassembled. Almost every thrust washer and Torrington bearing were wiped out. The old-timers out there, like my friend Phil, know exactly where I’m going with this. On the 350’s, it was due to a bad ground. Those pesky electrons were traveling through the shift cable, which was also failing, and transmission parts through the driveshaft and the rear axle.

The repair was installing two braided ground cables--one from the cowl (firewall) to the wing nut at the carburetor and the other was from the bottom of the cowl to a bolt on the bell housing securing the transmission to the engine.

As I explained to John and Greg here in Shepherdstown, some thrust bearing premature failures have been attributed by poor engine grounding. When the starter motor is engaged, electrons need to go to ground and if the engine isn’t properly grounded, current can run through the crankshaft and directly into the thrust bearing’s steel backing. In time, the thrust bearing faces can rapidly eat away, behaving as if the thrust surface on the crankshaft isn’t finished properly.

It’s simple and necessary to check for too much voltage in the drivetrain. You simply connect the negative lead of your DMM to the negative post of the battery, and the positive lead to the transmission. You should see no more than 100mv on your meter while the starter is cranking for about 5 seconds. Although the most current flow usually occurs while the starter is cranking, current in the drivetrain can happen while accessories are operating. That’s why you should perform this voltage drop test with the ignition on and as many accessories operating as possible. Again, the maximum is 100mv. If the voltage is too high, check or replace the negative battery cable, or add ground straps from the engine to the frame; or from the transmission to the frame. Some systems may reach 300mv briefly without causing a problem. For added assurance, improve the ground with a larger battery cable or additional ground straps.

“Is it possible that there is too much latent current flowing through the drivetrain, but without measurable voltage?” Greg asked.

“Sure,” I said, remembering one I dealt with about a year ago. “If you have a ground issue in the chassis, but the transmission and engine grounds are fine, the vehicle could pass the test, because the driveshaft and suspension components become the ground path. Saturn Vues going through wheel bearings can be the result of this.”

“So, how would you check that?” John asked.

“I pull the driveshaft and then measure the voltage drop. Now the frame and drive train must pass the 100mv test. Then you run a ground strap from the engine or transmission to the frame.”

“Remember the rear brake caliper slide pins freezing on W body cars years ago?” My friend Phil reminded me. “The engineers finally determined it was due to the static electricity created be the friction of the pads against the rotors looking for a ground through those mounting pins.”

John and Greg are great technicians who take pride in their work and I was glad to have an opportunity to help them out.

Haunted Car?

Can a car be haunted? On a muggy night in South Africa in 2004, a Renault Megane turned itself on and began jumping backwards, all on its own. This car is notable because there were several witnesses and news reports. Nine people, including two police officers, heard the Megane's engine start before it "jumped" backwards twice uphill, according to officials. The car apparently roared to life on its own, despite having no keys in the ignition and the parking brake engaged. I thought the 2006 Lincoln LS with a 3.9 was haunted. It came from Shepherdstown, a nearby town so haunted that the local police called in “Ghost Hunters” from the TV series. The LS Sport came from a couple of different shops for intermittent misfires, stalling, MIL on and transmission shifting issues. The work history indicated the plugs were replaced, TAC module was replaced, The PCM was replaced multiple times, the fuel pump replaced and coil assemblies were replaced. The throttle body was cleaned. Road test #1 resulted in an engine stall—just like the ignition was shut off. After the vehicle restarted, a P0607 flagged. The PCM’s internal CPU has encountered an error. This could be a calibration update, or aftermarket performance parts installed, or a damaged PCM. Clem came back with another PCM (number 3) and wants me to install it. I said no way. I did a visual inspection first, especially focusing on the PCM considering it was replaced before. Guess what? I found a damaged CAN (+) wire had several broken strands. I did a wire repair, confident that this was a major issue. I continued testing, though. I checked the ground circuits first. I prefer testing the ground circuits first because the remaining circuits will use this ground to verify they are working correctly.  This includes battery cable connections, which are subject to corrosion. No trouble found. Once the grounds are checked, I then move to the voltage circuits starting with B+ voltage because the Ignition, voltage reference, and control circuits require a functioning B+ circuit. B+ is direct battery voltage to a module or component. Those circuits were good. I checked the ignition circuits which includes ignition circuits that pass through a fuse, module, component, or connection.  When testing ignition circuits, I referenced the wiring schematic as to the ignition switch mode or position needed to achieve a valid reading. The ignition circuit test is referenced to the ground or low reference circuit and requires a functioning B+ circuit for a viable test. I checked the reference voltage circuit next, which is referenced to the ground or low reference circuit and requires a functioning ignition circuit. Satisfied that all PCM circuits were now acceptable, I moved on. Road test #2 flagged a P1270 (Engine RPM or Speed limit reached) and P2112 (TAC Control System). I checked data PIDs IACTRIM and IACKAM2. The sum of IACTRIM and IACKAM2 is the total IAC. Total IAC was 0.54 lb/min. I removed the throttle body and cleaned the edges of the throttle plate and throttle bore. It was bad. I reassembled it and took the vehicle on road test #3. This one resulted in an engine stall—just like the ignition was shut off. After the vehicle restarted, a P0607 flagged. The PCM’s internal CPU has encountered an error. This could be a calibration update, or aftermarket performance parts installed, or a damaged PCM. Clem wanted me to install that PCM. I said not yet. I already checked for the common bad coil issue. I always check the Coil-On-Plug ignition systems for defective coils by back-probing the main coil B+ with my PicoScope on glitch capture and using an injector as cylinder reference. I put the coils through the tests, including idle testing, cold, hot, snap throttle and power braking. With throttle cables gone, plus the 6-way BPPS, it is tougher to check these functions under the hood. I always look for a positive or negative voltage spikes on the coil ignition feeds which will indicate the failing coil(s). This car passed this test with absolutely NTF!

“This car is haunted,” Clem said.

“I have to walk away from it for a while,” I said.

“You can’t fix it?”

“No—I haven’t fixed it. I don’t throw in the towel but I do need a break.”

I thought about it while watching the Shenandoah River go by. A shop said they cleaned the throttle body and I could tell they didn’t. Did they even change the plugs? That was on my list of things to do when I would tackle it again.

“You must have one heck of a load, Bob, with all those cars and trucks to diagnose,” Clem said.

Then it hit me. I smacked my head as a token gesture.

“One heck of a load—you are so right, Clem!”

“Huh?” Clem said.

I got out my extra long test leads and went for a test drive. And I caught it--an ignition voltage spike! Right after the spike I lost the injectors. I also wanted to check that TAC module issue. With my PicoScope hooked up to ignition primary, and both throttle position signals (one on glitch capture), I captured a voltage spike on the TPS signal. The voltage spike is what caused the TAC codes.

The coil failed under a heavy load, hitting the PCM with the spike, causing it to reset.

More history of the LS Sport surfaced. The fuel pump was replaced because the original owner jump-started the car with a heavy-duty diesel truck charger on boost. Why did he do that? Because he was tired of the old battery going dead, procrastinating on buying a new battery, and after the original battery would take a charge, he decided to boost it. After that, he noticed the PCM would not drive the fuel pump so he had the car towed to a shop and had the technician replace the fuel pump.

The COP units were replaced, but a new one was bad to begin with, failing only under very high load. The ghosts were finally “exorcised” from the Lincoln.

I was so happy to get this one diagnosed.

“How can I thank you?” Clem was elated and hugged me and kissed me on the cheek. Now, don’t think that was weird. Clem is short for Clementine.

“You can really thank me by paying my bill, Clem,” I said, handing it to her.

“Now—that’s scarier than any ghost,” she said, after seeing it.

“I can put the ghosts back in the Lincoln, then.”

Clem paid.