HiTech Diagnostics, Inc. was called out to investigate a 2008 Pontiac G8 for an intermittent no-start and the Security telltale was illuminated. I stopped out to the shop and met Larry, the technician working on the car.
"Step one after filling out a good, solid customer concern sheet is to verify the concern," I said, as Larry worked on the car.
"Yeah, well, it starts for us," he said, showing me. I looked over his shoulder as he scanned for trouble codes. "There is a code in the body computer," Larry said, pointing to the B3060.
"Does this car have a work history on it?" I asked. Another question to ask early on in the investigation.
"The 10-minute relearn was performed and I cleared the code but the customer brought the car back for the same problem. I replaced the theft deterrent module and now the car started and stalled. After that, it came back for an intermittent no-start. I would appreciate it if you can get this Pontiac out of my hair."
I looked at Larry's balder-than-bald top, wondering what he meant by that comment. I thought about how the system works. There is a small transponder chip embedded in the head of the key that is energized by what the manufacturer calls "exciter coils" surrounding the ignition lock cylinder. With me so far?
Well, that tiny chip transmits a signal that the theft module grabs and compares it to a value it has stored in its memory. There are a couple of basic transponder keys--encrypted and zero-bitted. Anyway, the code stored in the module memory is the learned key code. If the value is correct, the theft module sends out a pre-release password over a data line to the engine controller. Now, if that transponder signal doesn't match the learned key code or if it doesn't receive a signal, the theft module tells the engine computer to cease and desist engine operation. Now, the driver is in Leather Personnel Carrier Mode. He or she is walking.
"Look--don't teach me how it works, just tell me how to fix it," Larry said, frustrated over my explanation.
"Please tell me you did some research, Larry--any service bulletins?"
"None that helped," Larry said. I remembered an SUV once with Articulating running Boards that quit working after someone replaced a control module. I spotted the Manufacture Enable Counter (MEC) was reading 8. This meant I had to cycle the ignition key eight times because that counter is supposed to read 0. We reset the counter to 0.
Next, I checked out the B3060.  The theft module was saying that the transponder signal received was either wrong or not learned by the vehicle.
"Where are the rest of the keys?" I asked Larry. I want both keys to do the relearn. Well, the customer was contacted, brought the other key with him and he also brought the culprit: a key tag that links to his credit or debit card so he can pay at the pump. Well, the radio frequency was interfering with the transponder chip and the module. The immobilizer operates at 125 kilohertz frequency. RF devices that operate in the 120 kHz to 135 kHz, or a multiple thereof, it can cause interference.
"Come to think of it, the car only acted up when I refueled it at the gas station that took my pay-at-the-pump toy," the customer finally admitted.
All the guy had to do was to move the RF device away from his key. End of problem.
"Thanks a lot, Jack, Larry said. "How can I show my gratitude?"
"You can pay me," I said.
"Okay, do you take Radio frequency payments?" Larry asked.
I shook my head. "Too much interference, Larry."
It is 11:00 PM on Saturday, April Fool's Day, and I just got home from Larry's shop. I'm tired. At least this will be fodder for my upcoming new thriller.
Until next time, this is Jack McGinnis, HiTech Investigations, signing off.