OK Guys I have a problem that I cant figure out. The problem is that my Check Engine Light (CEL) which I feel is electrial in nature instead of an engine problem. The CEL is supposed to come on when the switch is turned to the ON position to verify that the light actually works then turn of when the switch is turned to RUN. My CEL started to NOT turn on when the switch was turned to the ON position but it would turn ON and stays on when the switch is turned to the OFF position, stayd on even with the key out, causing a battery drain and perhaps a fire hazard. My code reader shows no codes and the car performs like normal. I tried disconnecting various circuits and have found that the CEL goes out when the courtesy light fuse is pulled. The courtesy light timer is working normally but I disconnected it completely.....CEL still stays on. I pulled the center cluster and checked the harness as well as possible with nothing unusual found. I have good electrical diagram but I'm no electrical engineer and find some of it confusing. I can do without the courtesy lights but prefer things to work as they should. Is it possible that the ignition switch itself is the culprit? The ignition seems to work properly and feels "normal". Today I plugged the courtesy light circuit fuse back in to try to do some more troubleshooting. Turned the switch to ON and after a few seconds I smelled a burning odor and found that the ECM in my battery compartment was fried. Got a new (ramanufactured) ECM today and got it installed, hoping that it would cure the initial problem but it didnt. I am essentially back where I started. Apparently something electrical is overloading the ECM. The car runs fine but something is obviously very wrong here. Any ideas would be appreciated.

 

Sounds like a wiring short issue in your harness possibly or even your gage cluster. The ECM supplies a ground to the CEL to turn on. If this specific wire from the ECM to the gage cluster has an insulation breakdown, then you may have the short to ground to turn on the light.

The dirt of it is your may need to rip apart your interior to expose the main wiring trunk that goes from your 2 ECM connectors up towards your dash under the shifter console. I would inspect this area to look for possible melted insulation on any wires to determine if that's your problem location. A 'SERIOUS' PITA!! Use a good bright small LED flashlight to help spot check your wiring. This made life alot easier for me when I rewired my car for the LS1 swap I just went through.

Sometime just separating the wires from each other is enough to see if the condition goes away or not.

Maybe you can let your nose to some detective work, once you start dismantling things.

I suppose the alternative is sell the car and have a strong drink.

Interested in hearing what you find.

 

This is going to be a tough one. Lets try to simplify it.

You have two wires to consider. The brown with the white strip comes from the ECM. The pink with the black strip comes from the guages fuse...thats the 20 amp fuse.

First locate the buzzer module. Its a box the size of a cigarette pack plugged into the fuse panel. Its got a couple of wires going to it. Unplug the module from the fuse panel(just pull) but do not disconnect the wires. Thats the way mine is because it blown.See if that solves the problem.

Or the problem could be in the delay timer.If it doesn't pull the guage fuse. If the light still goes on then the problem is a short somewhere. Its either in the brown with the white strip going to the ECM. or on the circuit board behind the center cluster. You need to be carful with plug if it touches two copper strands then things are being cross powered.

Your problem most likely is in either the dimmer or buzzer or delay timer circuit. The courtesy delay timer is to the right of the glove box(remove glove box to see it)When you turn the key to off these are they only things that are on. You need ti isolate which circuit. Its a process of elimination.

Try the above. Start with the buzzer its probably been kicked a few times...bad spot for it.

Jim

 

Thanks Guys, Ill start on these tomorrow when I get home from work. I appreciate your input and any others that have ideas as well.