Strange Electrical Problem

**jcws6** · 10-10-2008, 10:03 AM

A couple months ago, I purchased a "93-02 Firebird/Camaro Passenger window fix kit" from AutoTrix, for my 2002 Trans Am. A couple days ago, I found the time to begin the installation, and I ran the power wires per the instructions. I reinstalled the PCM and door panel, and drove my car. Everything was fine.

Today, I attached the other interior panels and finished hooking everything up. Both windows worked without any problems. However, when I started the car to drive it, there was a problem with my gauges. The speedometer, oil pressure gauge, and battery gauge all work OK. But the tach, gas gauge, and temp gauge don't work. Also, these warning lights are always on: air bag, TCS off, oil change, brake, check gages, ABS inop, and service vehicle.

I disconnected and reconnected the car battery, removed the power to the passenger window harness, and even removed the passenger window switch. The gauges still didn't work. I took my car to AutoZone for a code scan, and the guy said that the scanner wouldn't even read the PCM.

My car is in very good condition, I followed the instructions perfectly, and I have done several successful electrical installations before (remote start systems, car stereo equipment, etc.). My car had no problems until the time I connected the wiring harness, hooked up the battery, and started the car. I already emailed AutoTrix, and they say that the kit " in no way can interfere with the other electronics on your car."

Any suggestions?

**bills98ta** · 10-10-2008, 10:46 AM

When the OBD won't read, it might be the cigerette lighter fuse...

**2001NBMZ28** · 10-10-2008, 10:51 AM

Check all fuses first. The reason auto zone couldn't scan the car is probably because at least the CIG/ACCY fuse is blown - don't think they can read "service vehicle" codes anyway. If all the fuses are good try removing the kit and put the wiring back to it's original configuration.

**bills98ta** · 10-10-2008, 10:57 AM

Try reseating the harnesses on the PCM ?

**jcws6** · 10-12-2008, 09:25 AM

I disconnected & reconnected the PCM, and everything works now. Thanks guys!

**bills98ta** · 10-12-2008, 09:58 AM

Originally Posted by jcws6

I disconnected & reconnected the PCM, and everything works now. Thanks guys!

**ls1racer1999** · 11-07-2009, 06:30 PM

mine has a similar problem only ive tried to disconnect the pcm i even ordered new pcm and had it programmed then tried if i let mine sit for a few hours it will work then drops out and still cant connect to the laptop cant figure it out

**bills98ta** · 11-08-2009, 01:55 AM

Originally Posted by ls1racer1999

mine has a similar problem only ive tried to disconnect the pcm i even ordered new pcm and had it programmed then tried if i let mine sit for a few hours it will work then drops out and still cant connect to the laptop cant figure it out

Intermitting... Uhhmmm...
Did you try a different scanner or another PC & cable to confirm it's the car ? You could also add a ground wire to the ecm (pcm) on one of the four corner bolts to the ground post on the shock tower... I've seen that before.

**ls1racer1999** · 11-08-2009, 06:46 AM

hey thanks for the idea ill try that ! umm the scanner is good ive tried it on other vehicles .theres no communication to the dlc im not sure what other circuts would control that circut . i added a new pcm cuz i had tested every thing up to pin 58 dark green wire and was pretty sure thats what the problem was but it wasnt im going to remove all the grounds and try and clean then all very good again . its just frustrating i had driven it for weeks and then just one night i put it way and the next day it went out if i let it sit for a day or 2 then try it it will work for about 5 min then die out fuel gauge,coolant temp,tach all die out and there is no communication to the dlc. few days prior the alt started going bad i installed new alt . and it worked for a few then died out again ( the gauges)

**bills98ta** · 11-08-2009, 07:00 AM

I'm not what all the body control module does, but it's located behind the glove compartment. Maybe reseat that connector too...

**jcws6** · 11-08-2009, 05:03 PM

I'm wondering if this might be a short in one of the wires in the PCM harness. I know that's not much help, but I'd recommend checking all of your fuses, then starting to test the wires in the harness with a multimeter. Maybe the PCM isn't actually getting power.

IMPORTANT WIRES TO TEST ON PCM:
- Blk/wht = ground
- Tan/wht = ground
- Orange = battery
(For V8 car, info from Haynes manual electrical diagram)

Have you checked the alternator harness and had the your charging system tested? It sounds like the problem might've started with your alternator, so that might be another thing to test.

**ls1racer1999** · 11-08-2009, 06:18 PM

Originally Posted by jcws6

I'm wondering if this might be a short in one of the wires in the PCM harness. I know that's not much help, but I'd recommend checking all of your fuses, then starting to test the wires in the harness with a multimeter. Maybe the PCM isn't actually getting power.

IMPORTANT WIRES TO TEST ON PCM:
- Blk/wht = ground
- Tan/wht = ground
- Orange = battery
(For V8 car, info from Haynes manual electrical diagram)

Have you checked the alternator harness and had the your charging system tested? It sounds like the problem might've started with your alternator, so that might be another thing to test.

hey ill test them tomarrow thanks. the alt was going bad a day or so before this happened. then after it happened i changed the alt so the alts new and the wire comming out of the top is good and tight and seems to be working correctly i checked all grounds on the engine and on the chassis still no luck its odd i can let it sit for a few days try it and it will work for a few min then all of a sudden those gauges drop out and car seems to develop a mis i tried a new pcm and everyting still did the same thing after a few min im hoping i didnt burn the new one out