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Topic: ECM issues

in Forum: C4 Driveline Components


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ECM issues (1/11)
 5/19/16 7:45pm
Hals94
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Mount Vernon, ME - USA

Vette(s):
1994


Joined: 4/23/2012
Posts: 16

I lost 3rd gear and od in my 94 Lt-1 automatic. Had the trans rebuilt and now the shop informs me that the ecm is what caused the trans to fail. They are trying to find a used replacement. I called corvette central and they told me to have it rebuilt would take 4 to 6 weeks after they receive mine. I haven't tried the dealer yet but I can't imagine the price of it. Any ideas??? It is just getting into the season and I have been waiting for 3 weeks already to use it. Help!!!!! Hal
 
 
 help PLEASE
 


|UPDATED|5/19/2016 4:45:05 PM (AZT)|/UPDATED|
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Re: ECM issues (2/11)
 5/20/16 8:51am
Black Shark
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Vette(s):
Black 1979 L-82 Black 1996 LT1 Black 1999 Coupe


Joined: 3/20/2009
Posts: 611

I know a lot of people use PCMforless
 
 
 
 
I don't have experience with them, but I have heard good things.


|UPDATED|5/20/2016 5:51:31 AM (AZT)|/UPDATED|
Re: ECM issues (3/11)
 5/21/16 10:19am
Hals94
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Mount Vernon, ME - USA

Vette(s):
1994


Joined: 4/23/2012
Posts: 16

Thanks, I called and they have what I am looking for. Now I am trying to understand what is causing the torque converter to not lock up. The trans works ok but the t/c don't get the signal to lock up. Any one with experience on this problem?
Re: ECM issues (4/11)
 5/22/16 10:37am
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Is it setting any CODES? If you're not getting a "TCC stuck off", or other lock-up codes, then the PCM is not commanding lock-up. Coolant temp, TPS, vehicle speed, and various other sensors could keep the PCM from commanding lock-up...need to determine if the PCM is commanding lock-up or not first.
Why do they/you think the PCM is what caused the 3-4 clutches to fail, anyway? The 3-4 clutches on any 700/4L60E is the weakest link in the trans to begin with, and there are several things that can cause them to fail, but....the PCM is not usually one of them.

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Re: ECM issues (5/11)
 5/24/16 11:33am
Hals94
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Mount Vernon, ME - USA

Vette(s):
1994


Joined: 4/23/2012
Posts: 16

Thanks for the help, I am being told that the only code being set is code (83) I don't find 83 on the list of codes that is associated with the trans. Again I did not see the code myself so I can't say for sure if it is the one or the only one. The vehicle is still In the trans shop with a good sized bill against it and the owner has offered to buy it for a really low price so I question  what is real and what is not. I don't know what my next step is. The shop is talking about the vehicle being a 94 and the trans is a 95 and it may or may not have the proper wire that the 94 needs for the lock up.
If it does then he thinks re flashing the prom will fix the issue.???? Again, Thanks, Hal
Re: ECM issues (6/11)
 5/24/16 10:59pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

83 is not a valid code for a '94 model....but it is for a '95. The code is for the TCC PWM solenoid, which the '94 model transmissions did not have. It's possible your car has a '95 model PCM in it....depending on the build date of the car. If it is a late build, it is entirely possible it came from Bowling Green with the '95 spec PCM and trans. The 83 code is also purely electrical. The PCM  sees either a short, or an open in the PWM solenoid circuit. If the trans does NOT have a PWM solenoid, that's the problem. If it does, then the solenoid, and the wiring to it from the PCM needs to be checked.
My guess is they dint actually rebuild your trans...they installed a "stock", already rebuilt unit in the car, and it is the wrong year model for the PCM. Whatever the issue turns out to be, don't sell the car to them!!!! The guy may be telling you a tall tale just so he can buy the car cheap!! I'm assuming you didn't have this problem before, correct? That should tell you something....it sounds to me like they screwed up, and want you to take the loss on it.....don't fall for that crap.

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Re: ECM issues (7/11)
 5/25/16 2:19pm
Hals94
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Mount Vernon, ME - USA

Vette(s):
1994


Joined: 4/23/2012
Posts: 16

My thoughts are the same. You are correct, I didn't have any issues until I lost 3and 4.  I never asked if the trans. was mine or one that he had in stock and I don't know the history of the car so I don't know if it had been changed before I purchased it. The shop has told me that the reason for the 3-4 failure was overheating from the failure of the lock up. He also said that it will overheat again if not solved. I don't think that I will sell it to this guy but I still don't what to do if I bring it home. It would be difficult to find another shop to work on it after this has been done. Thanks for your help,Hal
Re: ECM issues (8/11)
 5/25/16 10:58pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

I'll politely disagree about no lock-up causing the loss of 3rd/4th. True, tho, that no lock-up will cause the trans to run hotter than "normal", but only on the highway for extended periods. Even then, it would not cause the 3-4 clutches to fail, unless it got hot enough to puke the fluid out, and someone continued driving with in overdrive no/low fluid....in which case it would be driver error/neglect.
You can drive the car with no lock-up and not have any problems, other than a loss of fuel mileage. I wouldn't recommend any extended road trips for sure like that....but if they refuse to correct the problem, or insist they dint create the problem themselves, get the car out of there....and find a real shop that can diagnose the real issue and repair it.... Smile

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(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: ECM issues (9/11)
 5/26/16 7:55am
Hals94
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Mount Vernon, ME - USA

Vette(s):
1994


Joined: 4/23/2012
Posts: 16

Sound advise. I will be getting it out of there and looking  for a mech. that knows vets.
I will let you know how THAT WORKS OUT.  Thanks for all of your time and help.  Hal
Re: ECM issues (10/11)
 5/28/16 10:00pm
Hals94
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Mount Vernon, ME - USA

Vette(s):
1994


Joined: 4/23/2012
Posts: 16

I still don't know how the 95 trans was installed And at this point I guess it don't make much difference. I now have the car back and the story goes like this, the mechanic worked with a Chevy mechanic and with my original PCM he added a wire to it to control the TCC and we no longer have code 83 being set it seems that the connecter to the trans has a pin to connect to so it all went well. I guess that with a vehicle with over 90K on it there might be a number of scenario's  that could have happened. I can see the wire added to the CPM but I haven't looked at the trans connecter yet. I have put about 100 miles on it and so far all is well. Thanks for all the help 
Re: ECM issues (11/11)
 5/29/16 12:10pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Good to hear you've got it back, and it appears to be working properly. Clap
What a pain, eh? 

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Joel Adams  
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(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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