2001 buick regal wire short between PCM and DIS

[tagreath]

I have a 2001 Buick Regal that has been a very reliable car for the last 4 years, however in the last two months it has given me lots of grief. first the indicator started flashing eratically with no light on the dash, The dealer charged me $700 to replace the "main lighting control module", then the transmission failed, which cost another $2,700 for a used tranny.
Now only a weak after having the tranny installed (by the dealer) the car has started to misbehave. I went to start it up to go to work and when i turned the ignition there was just a click and the engine did not turn over, I figured maybe it was an alternator or battery problem, i jumped the car from my wifes car and drove it to work (40 miles, mostly highway), the firing was a little erratic at first, however this smoothed out. When i got to work I turned the engine off and tried to restart it, again just a click and nothing. Upon further investigation in daylight, under the hood, there was a red/black wire that runs from the Ignition Control Module to the PCM, this wire was completely burned out, the insulation had melted and at one point the copper strands of the wire had melted together. I spliced another piece of wire in the burned out section and the car started and ran great. However, the car now occassionally cuts out and the wire is still burning out.
i know there must be a short somewhere, but the PCM is a sealed unit that i am not willing or qualified to interfere with.

Does anyone have any advice ?

Thanks
Terry

[GMMerlin]

Originally Posted by tagreath

I have a 2001 Buick Regal that has been a very reliable car for the last 4 years, however in the last two months it has given me lots of grief. first the indicator started flashing eratically with no light on the dash, The dealer charged me $700 to replace the "main lighting control module", then the transmission failed, which cost another $2,700 for a used tranny.
Now only a weak after having the tranny installed (by the dealer) the car has started to misbehave. I went to start it up to go to work and when i turned the ignition there was just a click and the engine did not turn over, I figured maybe it was an alternator or battery problem, i jumped the car from my wifes car and drove it to work (40 miles, mostly highway), the firing was a little erratic at first, however this smoothed out. When i got to work I turned the engine off and tried to restart it, again just a click and nothing. Upon further investigation in daylight, under the hood, there was a red/black wire that runs from the Ignition Control Module to the PCM, this wire was completely burned out, the insulation had melted and at one point the copper strands of the wire had melted together. I spliced another piece of wire in the burned out section and the car started and ran great. However, the car now occassionally cuts out and the wire is still burning out.
i know there must be a short somewhere, but the PCM is a sealed unit that i am not willing or qualified to interfere with.

Does anyone have any advice ?

Thanks
Terry

Your concern is not with a shorted wire, but most likely a bad or open ground. With the information presented in regards to previous work, most likely the ground is loose.
Lets start at the beginning. The wire (Red/Blk) is the Low Reference wire from the ICM to the PCM. A Low Ref is a ground supplied by a module..in this case, the PCM supplies a ground for the ICM. There is also a chassis ground for the ICM that bolts right under the coil/module assembly on the bracket.
Since you state that this started right after the Trans was replaced, I would check the ground for the PCM that bolts to the Left front side of the trans bellhousing near the starter.
It is possible that this is loose or not installed and the PCM is trying to find a ground path thru the ICM on the Low Reference wire.
Since the Low Ref is a .35 mm wire and the PCM has 4 grounds that splice into the .8mm wire to the trans, the Low ref is overheating causing the insulation to melt off of it.
Also check the battery ground at the trans also.

[tagreath]

Originally Posted by GMMerlin

Your concern is not with a shorted wire, but most likely a bad or open ground. With the information presented in regards to previous work, most likely the ground is loose.
Lets start at the beginning. The wire (Red/Blk) is the Low Reference wire from the ICM to the PCM. A Low Ref is a ground supplied by a module..in this case, the PCM supplies a ground for the ICM. There is also a chassis ground for the ICM that bolts right under the coil/module assembly on the bracket.
Since you state that this started right after the Trans was replaced, I would check the ground for the PCM that bolts to the Left front side of the trans bellhousing near the starter.
It is possible that this is loose or not installed and the PCM is trying to find a ground path thru the ICM on the Low Reference wire.
Since the Low Ref is a .35 mm wire and the PCM has 4 grounds that splice into the .8mm wire to the trans, the Low ref is overheating causing the insulation to melt off of it.
Also check the battery ground at the trans also.

Thank you for the advice, you were right on the money. The ground wire on the trans bell housing was not re-connected properly.
I took the car back to the dealer who replaced the trans and showed them the problem, they apologised for the trouble they had caused and replaced the burned out wire and tightened up the ground wire.
The car is running great again.
Thanks

Regards
Terry

[BNaylor]

Just out of curiosity how many miles do you have on your Regal?

$2700 for a used tranny at the Dealer????? Sounds like they got their money's worth out of you not to mention all the problems they caused by the ground. If were in the same situation I would not not be taking it so lightly. Just my 2 cents. Good luck!

[tagreath]

Originally Posted by bnaylor3400

Just out of curiosity how many miles do you have on your Regal?

$2700 for a used tranny at the Dealer????? Sounds like they got their money's worth out of you not to mention all the problems they caused by the ground. If were in the same situation I would not not be taking it so lightly. Just my 2 cents. Good luck!

The car has 190,000KMs on the clock. The used tranny had 45,000 KMs, so I was told.
The price of $2,700 CAD included labor and taxes.
You are probably right in what you say, but they have seen the last of my business, I will go elsewhere in future.

Regards
Terry

[BNaylor]

Originally Posted by tagreath

The car has 190,000KMs on the clock. The used tranny had 45,000 KMs, so I was told.
The price of $2,700 CAD included labor and taxes.
You are probably right in what you say, but they have seen the last of my business, I will go elsewhere in future.

Regards
Terry

Based on today's exchange rate and subject to my math, that's $2,305 USD versus $2700 CAD. I hope you got a warranty on the used tranny.

On the bright side you've gotten some good mileage out of your Regal so far to date. My hats off to you.

However, just to give you a comparison I'm in Texas, I had a certified rebuilt 4T65E tranny with 6 month warranty exchanged in my father's 2001 Chevy Impala LS (3800) with a similar 4T65E tranny for $895 USD with exchange, labor was $500.00 USD for the total swap out.

Thanks for sharing your experience with us.

BTW - Not all GM dealers are bad. My dealer which was also Cadillac took exceptional care of me and my Regal when it was covered under the warranty. I was just addressing the issue of the used tranny and cost but there is the Canada factor.

And thanks to GMMerlin you got the issue resolved.

[GMMerlin]

For the price you paid for a used trans, you could have gotten a SERTA (GM rebuilt) with a 3 year/50K warranty...

Glad you got the car fixed.

[maxwedge]

Congrats to GMMerlin, very good diagnosis on the problem, straight analytical thought process.

[tagreath]

Yes. Congrats to GMMERLIN.
I am not particularly good with cars and when this problem occurred I was reluctant to take it back to my dealers, because I thought they would tell me it was something else and hit me with a big bill again. So I decided to do a bit of research and came across this site by accident ( Thank god I did). Thanks to GMMERLIN I was able to get to the root of the problem and get it fixed at no charge.
In future, this will be the first place I look for troubleshooting.
Thanks again for the help.

[GMMerlin]

Originally Posted by tagreath

Yes. Congrats to GMMERLIN.
I am not particularly good with cars and when this problem occurred I was reluctant to take it back to my dealers, because I thought they would tell me it was something else and hit me with a big bill again. So I decided to do a bit of research and came across this site by accident ( Thank god I did). Thanks to GMMERLIN I was able to get to the root of the problem and get it fixed at no charge.
In future, this will be the first place I look for troubleshooting.
Thanks again for the help.

No problem..just glad you didn't call me GMGremlin (inside joke)
Welcome to AF and hope you will stick around...great people and great info