1992 LT1 faulty ECM replacement
Thread Starter
Cruising
Joined: Aug 2007
Posts: 10
Likes: 0
1992 LT1 faulty ECM replacement
Morning all,
I am new to 'vettes and know very little about them, but I think I have diagnosed the problem with my C4 thanks to searching this forum.
The car will start, but dies about a second later.
I read the fault codes and its showing a C41, H41 and H72. For module 4 (the ECM I belive) it displays 'Err' which I think means that it can not communicate with the module.
Do you agree that this would indicate a faulty ECM and that replacing it should be my next step?
Also, can anyone tell me where the ECM is located on this model and roughly what the retail price is for it? I am in the UK by the way so it might be a bit more expensive over here.
Many thanks,
Bryn.
I am new to 'vettes and know very little about them, but I think I have diagnosed the problem with my C4 thanks to searching this forum.
The car will start, but dies about a second later.
I read the fault codes and its showing a C41, H41 and H72. For module 4 (the ECM I belive) it displays 'Err' which I think means that it can not communicate with the module.
Do you agree that this would indicate a faulty ECM and that replacing it should be my next step?
Also, can anyone tell me where the ECM is located on this model and roughly what the retail price is for it? I am in the UK by the way so it might be a bit more expensive over here.
Many thanks,
Bryn.
Thread Starter
Cruising
Joined: Aug 2007
Posts: 10
Likes: 0
Thread Starter
Cruising
Joined: Aug 2007
Posts: 10
Likes: 0
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 66
From: Queensland, AUSTRALIA
If youre planing on spending that much to buy the ECM, you may as well try a battery first mate yeah, cause if it was working last time, there is no good reason why 6 months of no use would cause an ECM failure 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Burning Brakes
Joined: Aug 2000
Posts: 984
Likes: 1
From: Cincinnati OH
That's for sure. No local places had one when I checked a few weeks ago, and GM is all backordered on rebuilds. I ordered one through a dealer 3 weeks ago, haven't heard anything yet. They are around $160-$170, if I remember correctly. That is for a rebuilt one, GM does not make new ones anymore.
Safety Car
Joined: Sep 2002
Posts: 4,030
Likes: 6
From: Maryland
That's for sure. No local places had one when I checked a few weeks ago, and GM is all backordered on rebuilds. I ordered one through a dealer 3 weeks ago, haven't heard anything yet. They are around $160-$170, if I remember correctly. That is for a rebuilt one, GM does not make new ones anymore.
I would suggest a used one. The rebuilds can have issues.
I wish I had kept my 1992 spare; I shipped my wrecked 1993 vette away with it in there just to be fair to the insurance co. but I doubt they cared.
Melting Slicks
Joined: Dec 2004
Posts: 2,541
Likes: 773
My '90 coupe is on its third ECM in as many years. The first one came with the car, and I don't know how old it was. The second one came from a junk yard and was installed an independent mechanic. I installed the third one, which is a reman.
Another mechanic explained to me that the soldering gets hot and the connections inside the ECM go bad. If mine goes bad, I'm going to check for lose connections and have the soldering gun ready. I put an ice pack on mine after each drive when I arrive home. So far, this ECM has performed better and lasted longer than the other two. I don't know if the ice pack is doing any good, but the ECM gets almost too hot to touch after I've driven the car for 20 or 30 miles. Seems stupid that Chevy put the ECM on only inches away from the hottest part of the engine.
Another mechanic explained to me that the soldering gets hot and the connections inside the ECM go bad. If mine goes bad, I'm going to check for lose connections and have the soldering gun ready. I put an ice pack on mine after each drive when I arrive home. So far, this ECM has performed better and lasted longer than the other two. I don't know if the ice pack is doing any good, but the ECM gets almost too hot to touch after I've driven the car for 20 or 30 miles. Seems stupid that Chevy put the ECM on only inches away from the hottest part of the engine.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 66
From: Queensland, AUSTRALIA
I put an ice pack on mine after each drive when I arrive home. So far, this ECM has performed better and lasted longer than the other two. I don't know if the ice pack is doing any good, but the ECM gets almost too hot to touch after I've driven the car for 20 or 30 miles. Seems stupid that Chevy put the ECM on only inches away from the hottest part of the engine.
Something might be wrong if its getting too hot, its more than far enough away from any heat in the engine bay.
Thread Starter
Cruising
Joined: Aug 2007
Posts: 10
Likes: 0
Thanks for all of your advice guys.
I put the battery on charge last night so will go and try it out tonight. After over 6 months of no use its probably time for a new battery but the correct one here in the UK is just under $300 USD so thought it worth trying to charge the existing one first!
I spoke to a UK Corvette specialist who said that the ECM (or PCM as he calls it) very rarely go wrong which seems at odds to what you guys are saying.
I hope its not the ECM - cost in the UK for one is over $1000 USD and it sounds as if I will have trouble actually getting one anyway.
The UK specialist suggested checking out the alternator, fuel pressure and the fuel pump, but that would not explain the codes on the computer unless the flat battery is the cause of them.
Thanks again,
Bryn.
I put the battery on charge last night so will go and try it out tonight. After over 6 months of no use its probably time for a new battery but the correct one here in the UK is just under $300 USD so thought it worth trying to charge the existing one first!
I spoke to a UK Corvette specialist who said that the ECM (or PCM as he calls it) very rarely go wrong which seems at odds to what you guys are saying.
I hope its not the ECM - cost in the UK for one is over $1000 USD and it sounds as if I will have trouble actually getting one anyway.
The UK specialist suggested checking out the alternator, fuel pressure and the fuel pump, but that would not explain the codes on the computer unless the flat battery is the cause of them.
Thanks again,
Bryn.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 66
From: Queensland, AUSTRALIA
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The 94 and later ECM's had an aluminum case with cooling fins to help with heat dissapation. The 90-93 versions had a two-part sheet metal case.
There could be a problem with any one of the wires in the ECM harness connectors coming loose or simply a contact may have some corrosion. You should pull the harness connectors and check for any greenish material on the contacts. Sometime a bad ground wire is the culprit.
How powerful of a battery charger do you have? You may have to have a shop charge the battery with a charger that is capable of 15-20 amps. If the battery is fully discharged, it may take a initial "shock" of amperage to get it to take a charge.
There could be a problem with any one of the wires in the ECM harness connectors coming loose or simply a contact may have some corrosion. You should pull the harness connectors and check for any greenish material on the contacts. Sometime a bad ground wire is the culprit.
How powerful of a battery charger do you have? You may have to have a shop charge the battery with a charger that is capable of 15-20 amps. If the battery is fully discharged, it may take a initial "shock" of amperage to get it to take a charge.
Advanced
Joined: Jan 2004
Posts: 66
Likes: 0
From: Edmonton Alberta
I had the same problem with my 1992. Check out these links:
http://forums.corvetteforum.com/show....php?t=1764929
http://www.digitalcorvettes.com/foru...t=53168&page=1
I ended up going through 4 reman ECMs before getting one that works. The first three were all from the same company. The fourth one was from Cardone and it works perfectly.
http://forums.corvetteforum.com/show....php?t=1764929
http://www.digitalcorvettes.com/foru...t=53168&page=1
I ended up going through 4 reman ECMs before getting one that works. The first three were all from the same company. The fourth one was from Cardone and it works perfectly.
Burning Brakes
Joined: Sep 2003
Posts: 1,214
Likes: 0
From: Miami FL
I have the same exact problem with my '93. Sarts fine...after a drive and things heat up under hood, I get SYS flash with the ASR light on the info display, car will run perfectly in this condition, if i shut her off, it will not re-start as the light show continues...after a while ( and i'm guessing, after it cools down a bit) it will start and i get going...the light show starts and...I better not shut her off till I get home. The wait time to cool down varies,,,5 min. 10 min..but it will re-start. It is a pain to go anywhere and having to wait to get going again. I am doing a 383 now and it will suck if i can't get a new ECM.