Ghost in the Mirror

"I don't want to scare you, but ever since this Yukon was at the old, haunted Moundsville Penitentiary, its been having these strange electrical issues."
The 2017 Yukon's strange electrical issues Jim mentioned included intermittent no-starts and stalling, a SVC 4WD message at times on the DIC, and once it set a DTC U0403.
"Anything else?" I asked. It is very important to collect as much information as possible, including where the vehicle called home during its service life.
"Uh, yeah--if you star in the rearview mirror long enough, you'll see the mangled face of a convict that was butchered with a shiv," Jim added.
"That'll ruin your day," I said.
The vehicle started several times for me without a problem. We took it on a road test and the Yukon performed flawlessly. "Would you mind not staring at me in the rearview mirror, Tom?"
"He does look like that convict from Moundsville prison," Jim laughed.
Jim directed me to Moundsville prison: a stoic, imposing stone structure adorned with turrets and battlements, like a castle, its empty cells filled with regret. I pulled into the parking area, turned the ignition off--and then the ghost showed up!
The engine wouldn't shut off. "I can get it to shut down," Jim said. He opened the door and the engine shut off. Then it would not restart--it wouldn't even crank.
"Great place to be stranded," Tom said, "At a haunted prison."
I popped the hood release and grabbed my digital meter. I started at the battery, checking connections.
"They're clean and properly torqued," Jim said. "The starter was replaced about a month ago at another shop in an attempt to fix this thing."
I checked each fuse with my meter. "I checked them," Jim said.
"That's nice, but I'm checking them again," I replied.
Tom had a scan tool plugged in. "There aren't any codes," he said.
I came around to where he sat, behind the steering wheel.
"There's no MIL on," I said, "You should see the MIL with the key on."
I went back to the UBEC and tapped on the ignition main relay that sends ignition power to the ECM.
"The MIL light just turned on," Tom said. I told him to try starting the Yukon. It started.
"Let's get back to the shop," Jim suggested.
We found a poorly-tensioned terminal at connector 2.

That wasn't the end of our diagnostics. When Jim turned the ignition off, the engine kept running until I opened the door. This Yukon came from Mansfield, Ohio. They use a lot of road salt and saline. This acted just like a ground issue. I looked at the schematic and spotted a splice location under a sill plate. Sure enough, the white, salty film was under the plate. J308 had been eaten alive by sodium chloride.

No more ghosts!!

The Highwayman

“My truck was running rough just before it stalled out,” the driver told us. It was a 2017 Kenworth and the driver, Max, was really pleased to see us. He called Dewey’s shop while we were having lunch.

When we got out there, we verified the concern. The Cummins engine cranked but it wouldn’t start. Milton conducted a thorough visual inspection while Dewey questioned the driver. No add-on equipment and no previous, recent service had been performed. The engine oil level was good and no parasitic load while cranking. Engine cranking speed was good. These technicians wanted a recommended diagnostic procedure to follow, so I offered my typical routine.

I check ground circuits first because the other circuits will use ground to verify they are functioning properly.  This includes battery cable connections.

Low reference circuits are checked next because the other circuits will use this low reference circuit or ground circuit to verify they are functioning correctly. A low reference circuit test requires the ground circuit between the control module and the battery negative terminal is intact. Testing for continuity on a reference low circuit oftentimes requires certain pre-conditions to attain a legitimate reading. Some conditions could include the ignition to be off for a certain amount of time, the ignition key needs to be out of the ignition cylinder, the scan tool to be unplugged or require a fuse to be removed in order for the module to power down.

The grounds were checked for integrity on the Kenworth—they passed a good visual inspection, and a voltage drop test.

Once the grounds were checked, we focused on the voltage circuits starting with B+ voltage—why? Because the Ignition, AC, voltage reference, and control circuits require a functioning B+ circuit and B+ is direct battery voltage to an ECU or component. A switch type device does not interrupt this circuit (Un-switched). This includes battery voltage circuits that pass through a fuse, ECU, component, or connection. The B+ circuit test is referenced to a ground or low reference circuit. It really depends on the circuit.

The B+ circuits all had the proper voltages, and the voltages were clean when checked with my scope.

The next voltage circuits that we tested were ignition voltages because the voltage reference, any AC circuits, and control circuits require ignition voltage to be present. An ignition circuit provides a switched voltage to an ECU or component when the ignition is in the OFF, ACCESSORY, ON or CRANK positions.  This includes ignition circuits that pass through a fuse, ECU, component, or connection.  When testing ignition circuits, I reference 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.

Do you notice that each test builds on the previous test?

Since the Kenworth had inverters, we checked all AC outputs. They were all consistent and clean. The AC circuit test is referenced to the ground or low reference circuit and requires a functioning ignition circuit, which was checked previously.

We inspected and verified the correct fuel pressure in the tanks; the OEM fuel shutoff valve was open. There were no component changes made to the CPL or engine components. Fuel regulator outlet pressure was good, within specs. The fuel regulator outlet pressure was within specs.

As you can plainly see, there is nothing magical about diagnosis. It’s always about a plan.

The fuel pressure after the fuel shutoff valve is detected by an engine fuel regulator outlet pressure/temperature sensor. The ISL G Module incorporates a boost reference low pressure regulator that helps in fuel control optimization across a full range of fuel flows. It can bump fuel pressure at the fuel control valve responding to an increment of boost pressure. An external pneumatic hose with fittings provides boost reference to the low pressure regulator to sealed end cap.

So far we were coming up with nothing. I’d gotten into diesel fuel sampling. I don’t have or need a Bacon Bomb Thief, but I do have a field test kit. I can check for both suspended and free water in fuel, and microbial growth as well.

I’m sitting in the Kenworth’s cab, trying to figure this one out, when I spotted it on the floor. I picked it up.

“What are these—feathers?” I asked Max, the driver.

“Yeah—duck bottom feathers, from near the preen gland,” he said.

“I never heard of them,” I said, “What are they used for?”

“Well, they’re buoyant,” Max said, “due to preen oil produced by the preen gland. I use them to tie dry flies.”

“For fly fishing,” I said. Max nodded.

“I bought them from the guy who tuned my engine the other day,” he said.

There it was—the answer! “Hold everything!” I said. “What are you talking about?”

“I’m at a truck stop, checking my rig over, when a guy in a new BMW SUV pulls up next to me. He was one fancy dresser, I’ll say that,” Max said. “He wore a lambskin leather blazer and one of those derby bowler hats. He looked well-to-do and said he was able to program my truck to improve my fuel economy and performance for only fifty bucks with a money-back guarantee.”

This was it. This was what we were looking for.

“At first I was doubtful, but then I saw his fly-fishing rod in his BMW, and since I’m an avid fisherman, we got to talking. The guy threw in a bag of Cul-de-canard in the deal—for free.”

This guy preyed on truckers. What he did was used his laptop to go into the ECM, maxed out the injectors and ruined the flow rates. Sure, the engine gained some power, but it wasn’t smooth power and the idle roughened up. Eventually the engine loaded up and finally wouldn’t start.

“I asked you if anyone worked on your truck and you told us no,” I said to Max.

“Right—nobody worked on my rig—all this guy did was reprogrammed my computer. That’s not the same thing, is it?”

See what you need to be wary of? Had I not seen those duck feathers, I might have missed this one. I reset the injector flow rates, cleared the lines, recommended an oil change and made the driver happy until he saw my bill. He wanted to square his debt by giving me the bag of feathers. I explained to the driver that I charged for diagnostic time. The software program that “Dick Turpin” used was clever. It changed the injector flow rates but showed a modified value on the data PIDs, to mask the high flow rates. Dick Turpin was clever. I call him that after Dick Turpin, the English highwayman whose exploits were romanticized following his execution in York. A highwayman was a robber who stole from travelers. At one of the diesel fuel stops, the manager told me of “an Englishman” who used a Bacon Bomb Thief to sample his storage tank and tried to sell him some snake oil.

The feathers “quacked” this caper.

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.