Help with C3 electrical problem
Thread Starter
1st Gear
Joined: Nov 2004
Posts: 1
Likes: 0
Help with C3 electrical problem
When I bought my 1982 a few years back the instrument cluster never worked. I recently took it apart and found the plug in back was not pushed in all the way. After pushing it back in the cluster works, but the check engine light now stays on when the car is off. As soon as I turn the key to any possition, the light goes off. I know it is a long shot that thier is a simple fix to any electrical problem, but I figured it is worth a shot. Any advice would be helpful. Thanks
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Can't speak to the 82 exactly, but most GM use a pink, 12v ignition switched wire for power to the service engine light and the ECM supplies the ground. I think the ECM would supply the ground with ignition off, but I don't understand how you could be getting power. I suggest a good wiring diagram and find out how you are getting power with ignition off. Bad ignition switch? Bubba wiring? Short in wiring?
Don't just pull the bulb. The service engine light is there for a reason. Find, the problem, it could be a fire waiting to happen.
Don't just pull the bulb. The service engine light is there for a reason. Find, the problem, it could be a fire waiting to happen.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
The check engine light circuit is rather simple. It is supplied voltage from the switch and it is grounded by the computer. So what is happening? Voltage is being suppllied with the switch off and the computer or something else in the wire is grounding the circuit. There are check proceedures outlined in good manuals that will isolate the problem area, but I would go back to that plug in and make sure that the tabs on the circuit board are attached and straight. It is common for them to get loose and short across the adjoining terminal.
