I was relocating the PCM underneath the windsheild wipper cowl. (saw in an earlier post) While doing this I accidently diconnected the connectors before I disconnected the positive battery cable. Now the car idles at the normal RPM but it runs really rough, and gives off a smell. Is it possible that I might have done damage to the PCM its self or a senser. Feedback will be greatly apprieciated! Thank you.

Hi,

Is it possible you did damage? Yes, it is. Unless the ignition key was on the unit should have been dead, they aren't energized all the time, only when running.

If is more likely you bumped something else in the process loose. Today's cars also "learn" how you drive and adjust themselves accordingly.
Make sure everything is plugged in tightly, don't just look, push and pull on the obvious connectors you could of dislodged. Check the plug wires and obvious damage or shorts. Take it for a ride, generally about 100 miles and if it is the engine control programming it should reset itself properly. Just be aware of your engine and what is going on if you have any doubts about safely going for a ride with this situation.

As a safety rule, disconnect the minus (-) side of a battery, it's just proper / good shop practice. Leaving the ground hooked up and the + wire off opens you up to accidentally making contact with the positive terminal thus creating a spark and possibly experiencing a battery explosion. Admittedly rare but it does happen and the results are NEVER pretty, you can be scarred for life, possibly killed from acid and fire.

Dave

I checked every connector that I might of even remotely came into contact with, still nothing. This idle is different, it almost seems like it's down 2 cylinders, it's that rough. After running it for about 3-4 seconds I can smell somethings not right, almost as if something is burning. I took the precaution of locating the + battery wire as away from the terminal so that contact was not going to be an issue. When I start the car it idles normal, but when I remove the spark plug I can smell fuel, So i'm starting to think it's an ignition problem. What is the proper way to do an ignition test?

UPDATE!!!

I tested the ignition system, and it looks like I was right. The wire on the PCM connector designated for the coil (cyl. 1&4) had backed out , causing the coil to lose spark. Once I fixed this however, the PASSlock system decides that it wants to step in and make an apperance. Now the car will turn but not start. Not sure on how to clear the PASSlock system, but i'll search a little more.

This should help you, I had to help a friend do his a few months back



00-05 J-car

1. Turn ON the igniton, with the engine OFF.

2. Attempt to start the engine, then release the key to ON (vehicle will not start).

3. Observe the SECURITY telltale, it will be flashing. After approximately 10 minutes the telltale will turn OFF.

4. Turn OFF the ignition, and wait 5 seconds.

5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes. The vehicle is now ready to relearn the PASSlock Sensor Data Code and/or passwords, on the next ignition switch transition from OFF to CRANK.

IMPORTANT: The vehicle learns the PASSlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You MUST turn the ignition OFF before attempting to start the vehicle.

6. Start the engine. The vehicle has now learned the PASSlock Sensor Data Code and/or password.

Update

Thanks EvoCav! That procedure worked great, but now the car still says "LOC" on the radio and my odometer says "Error". Not really sure what the problem is now, but I had my friend some over with a OBD-ll scanner. I passed the DTC's, but it says I have "Option Configuration Error", and my airbag light came on. At this point, i'm all ears (or eyes). The car runs as it should, but i'm worried about this "LOC" giving me problems.

I had that issue when i shorted out my BCM from messing with my running lights (totally a user error on my part)

If it is the BCM its located under the dash.. its a computer module that controls the lights, radio, odometer, ect.. looks like this




If that some how shorted out from a surge then you have 2 options..

1.pay a GM dealer WAY too much money to get it fixed/replaced..

2. go to a junkyard.. find a 00-05 (preferably as close to the same model in case something is different) If you have power windows/locks find a junker w/ power windows and locks and acquire the BCM.. some junkyards may not sell these things but just say its an A/C moduel or a radio computer.. (make note to not mention it being the computer that holds the odometer/miles) Then unplug the battery.. replace the module.. this will again activate the theft lock/ passlock.. repeat Ecocav's post.. then report back what happens..

We had to do the relearn on the brother 04 after he had the battery out of the car for a few days.



PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

When I replace the BCM with the one from the junkyard, will the odometer read the miles from the previous car?

so how do you relearn a 95-99 cavalier, I'm having the same problems with my cav. Thanks

chris b wrote:so how do you relearn a 95-99 cavalier, I'm having the same problems with my cav. Thanks

http://www.deserttuners.com/guide.php?id=9

UPDATE!!!


I disconnected the BCM and waited about 5 minutes. After I reconnected the BCM I had to do the re-learn the full 3 cycles/30 mins. When I attemped to start the car on the third time, it started. Shortly thereafter I noticed that the odometer was working (along with the trip odometer). The ABS light, service light, and check engine light disappered. I doubt there is a re-learn for the BCM, but it worked. The only thing that was not fixed by this was the Pass-lock on the radio. I suppose that I will just have to go to a GM dealership, but I was pleasantly surprised about everything else. I honestly didn't think that what I did would help, but thanks to everyone for commenting!

glad to hear its working again..

and to your question what ever BCM you have on the car working will be the odometer reading the car reads...