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.