Thread: Nothing computer controlled works! Many codes. No Gages/DIC/TCS/ABS and so on.

Driving to get lunch today and the DIC says "Charging system failure" followed by "Service engine soon" "service abs system" "service traction control" "Service variable steering" and a few others I didn't catch. It rebooted, showed the GP logo, and turned completely off. All my dash gauges flatlined, and the Aeroforce rebooted then shut off.

Stored in the Aeroforce is:

P0171 (System lean, from E85)
P0703 (Brake switch input low, been on since I bought the car, brake switch tested good, may be a BCM fault)

P1626 Loss of communication with the anti-theft fuel enable. Passkey error.
U1040 Loss of communication with ABS system
U1064 Loss of communication with DIM (dash gauges/DIC)
U1153 Loss of communication with CCP (Climate Control Panel, is that the BCM?)

Now, the car starts and drives normal, and the alternator is working (12v with car off, 14.2 running with headlights on). Except the dash comes alive and dies back and forth in about a 30 second cycle, and the ABS and PARK lights cycle on and off as well, but not in sequence with the dash, the DIC doesn't even light up, and the Aeroforce won't connect to the PCM.

Sounds like a BCM problem? Going to find it and unplug it and see if the connection got buggered up, as well as go test all the fuses. But this is pretty bizarre, only thing close I could find in a search was a ground stud being broken on a transmission.

Sounds like when some cars go into limp home when the Alternator dies and he battery gets really low then the accessories start dropping out. I would have to agree with Kyle about the grounds. Check the feed signal (red) and the PWM signal (Gray) and see what they are doing while the engine is running. If you have a meter that will read in Hertz (Hz) then select that place on the dial and probe the gray wire it should give you frequency if there is no frequency then see if it is either reading ground or full voltage. If it is reading full voltage with no frequency that would tell me that the PCM is stuck on for some reason.

And remember that 04+ has a voltage scheme that varies the voltage based on load so it is supposed to vary between 12.5-15.1

Jeff

Alright, update. Last night after work I checked the body ground coming off the battery and it looked fine but I couldn't get my arm in there to take the bolt off so it may need cleaning. What other grounds are there? Unplugged and replugged in the PCM, and any connectors I could find under the hood, but there was NO change.

Get in the car this afternoon to go to work and still the same issue. Give the DIC a gentle love tap and boom, it comes on, and the ABS/PARK lights go off. DIC only was reporting temp/compass, no tripometer,oil life,boost etc. Dash speedo started working too but no other gauges on the dash.

Leave work tonight and the only thing not working is the TCS, everything else works, all gauges functional including Aeroforce... While it IS sounding like I have a wheel bearing going bad, wouldn't that usually trip the ABS too? Could a short in the speed sensor cause other electrical gremlins like this?

Jeff, where would those wires be, the OBDII port? I do have an oscilloscope. Given the Aeroforce would only blink, it was seeing power but no signal on the OBDII port.

There should be another ground right around the battery tray area.


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Originally Posted by industrialfish

Alright, update. Last night after work I checked the body ground coming off the battery and it looked fine but I couldn't get my arm in there to take the bolt off so it may need cleaning. What other grounds are there? Unplugged and replugged in the PCM, and any connectors I could find under the hood, but there was NO change.

Get in the car this afternoon to go to work and still the same issue. Give the DIC a gentle love tap and boom, it comes on, and the ABS/PARK lights go off. DIC only was reporting temp/compass, no tripometer,oil life,boost etc. Dash speedo started working too but no other gauges on the dash.

Leave work tonight and the only thing not working is the TCS, everything else works, all gauges functional including Aeroforce... While it IS sounding like I have a wheel bearing going bad, wouldn't that usually trip the ABS too? Could a short in the speed sensor cause other electrical gremlins like this?

Jeff, where would those wires be, the OBDII port? I do have an oscilloscope. Given the Aeroforce would only blink, it was seeing power but no signal on the OBDII port.

They are located at the alternator. That will tell you if the signal from the PCM is working or not. Also there is a large ground in the engine block and one on the intake side close to the transmission.

Jeff

I'll have to check the intake side one, but everything works again this morning so even more proof of a wire being loose or dirty somewhere.

Intermittent problems suck. I have a 97 PA and the windows would stop working and when I got home they would work again, every freaking time.

Jeff

I didn't go into detail beacuse it wasn't my thread, but it was the pass side control module, and something else. Wasn't just the windows, was also the locks mirrors and latches. I replaced all 3 modules(each door and the one under the rear seat for the rear doors) and it would do it once every 6 months, where nothing worked. But I would get home or halfway home and all of a sudden it was like nothing happened.

Jeff