1990 Wiring / Short Issues
Thread Starter
Racer
Joined: Dec 2004
Posts: 470
Likes: 0
From: Phoenix Arizona
Phoenix 1990 Wiring / Short Issues
1990 Convertable with wiring short keep replacing ECM's and other signs of a short in the car.
I live in Phoenix if anyone on the forum knows of a good Corvette Mechanic that can find and repair an electrical short I would appreciate the referral.
Thanks
I live in Phoenix if anyone on the forum knows of a good Corvette Mechanic that can find and repair an electrical short I would appreciate the referral.
Thanks
Last edited by jghmczo6; Feb 14, 2007 at 05:25 PM. Reason: Place Location in Heading
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
with Casey on the "at least attempt" to repair the car. There is more fun in a Vette than just driving it 
What problems are you experiencing with the car to determine you have a "short" problem? Any codes stored in the ECM?
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
I can tell you now you'll pay through the nose for electrical trouble shooting....but here it's free. Can't help with a referal, but I'm curious who said the ECM was cooked? and how did they test it? don't know anyone who has the knowledge or equipment at least any forum members.BTW, have you had your alternator checked? most parts stores can do that for free.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Yep, replacing the ECM on a whim is a tall order in any case, and without the proper diagnosis attempts its also nigh on pointless, and id go so far as to say its "clutching at straws in attempt at a quick fix".
Having said that, its not out of the question for an ECM to fail, and without knowing anything about your circumstance, its impossible for us to even speculate anything that resembles a possibility at this stage.
Give us a shot though mate, you never know your luck, it may not be anywhere near as complicated as it seems.
Having said that, its not out of the question for an ECM to fail, and without knowing anything about your circumstance, its impossible for us to even speculate anything that resembles a possibility at this stage.
Give us a shot though mate, you never know your luck, it may not be anywhere near as complicated as it seems.
Thread Starter
Racer
Joined: Dec 2004
Posts: 470
Likes: 0
From: Phoenix Arizona
In 1991 the car was stolen from a dealer when I took the car in for a trans leak. The theif ran the car into a bridge abutment (concrete) did
13K in damages to the drivers side.
Signs of short
1.) This is my 4th to 6th ECM replacement since theft
2.) key chimes work intermittently
3.) alarm goes off each time I unlock the car
4.) Alternator replaced each 12 to 18 months
5.) Battery replaced each 12 to 18 months
6.) Had the turn signals replaced twice
7.) Replace the speedo cable reading 20mph to 95mph reading when doing 40mph
8.) Right (passenger side) horn does not work
9.) Replace fan relays three times
10.) and the list could go on...............
After inital problems with a independent mechanic most of the work completed by two Chevy dealers one in California and the other in Az.
Majority of the problems with this car are electrical and have been since the accident.
Thank You for all your help I really appreciate the responses received
after posting.
13K in damages to the drivers side.
Signs of short
1.) This is my 4th to 6th ECM replacement since theft
2.) key chimes work intermittently
3.) alarm goes off each time I unlock the car
4.) Alternator replaced each 12 to 18 months
5.) Battery replaced each 12 to 18 months
6.) Had the turn signals replaced twice
7.) Replace the speedo cable reading 20mph to 95mph reading when doing 40mph
8.) Right (passenger side) horn does not work
9.) Replace fan relays three times
10.) and the list could go on...............
After inital problems with a independent mechanic most of the work completed by two Chevy dealers one in California and the other in Az.
Majority of the problems with this car are electrical and have been since the accident.
Thank You for all your help I really appreciate the responses received
after posting.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
13k in damage to the drivers side? alot of damage. Can I ask this, was the battery damaged in the wreck? I mean you have a main bulkhead connection next to the battery and if a 90 is similar to an 87 you have a power tower behind the battery. I can just imagine what battery acid would do if it somehow hit the bulkhead connection or the power tower. I can almost guess what kind of problem that might cause. And I'd certainly have a look in to the bulkhead connection.
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Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Well i spose in 1991 $13k damage to a 1990 Corvette certainly wouldnt be out of the question from hitting a solid object Rick, it wouldve been a near $40,000 car back then.
The rest of your post (about the battery doing some damage) is very much what i was thinking too mate.
The rest of your post (about the battery doing some damage) is very much what i was thinking too mate.
Thread Starter
Racer
Joined: Dec 2004
Posts: 470
Likes: 0
From: Phoenix Arizona
Once the ECM is replaced the car operates fine with the exception of chimes,horns,alarm etc.,I believe after a while the areas where a short
occurs wears down the ecm and eventually causes it to fail somewhere else Fans, or car will not start or run.
1991 was a long time ago I do not remember if the battery or tower were damaged. My big contention at the time was frame damage the left frame rail bent inward, they straightened the frame however it is a few degrees off, especially with a front end alignment.
I can tell you the steering column moves to the left and up and down morer freely than it should apparently from impact. I do believe the battery was replaced. Do you believe the power tower should be replaced? And is the bulkhead connection behind the ecm?
occurs wears down the ecm and eventually causes it to fail somewhere else Fans, or car will not start or run.
1991 was a long time ago I do not remember if the battery or tower were damaged. My big contention at the time was frame damage the left frame rail bent inward, they straightened the frame however it is a few degrees off, especially with a front end alignment.
I can tell you the steering column moves to the left and up and down morer freely than it should apparently from impact. I do believe the battery was replaced. Do you believe the power tower should be replaced? And is the bulkhead connection behind the ecm?
Pro
Joined: May 2006
Posts: 583
Likes: 0
From: Pittsburgh PA
Just a very early thought would be a loose connection close to the battery. You are getting a voltage spike as the connection is effected, ie. the connection breaks down and then reconnects. That spike would fry the ecm and the lack of continuity would cause alternator problems. Question, do you have to jump start the car or charge the battery often?
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
If it were my car I'd damn sure want to look at the bulkhead connection, I mean take it lose and look to see if battery acid entered, one of the problems with the bulkhead connection is stock it has no sealant around it, something Gordon Killebrew suggest to do to keep water from entering. The tower behind the battery is quite visible with the battery removed. What I'd be looking for there is some sign of acid damage to connections as well as wires. Don't know exactly where the ECM is located on a 90, the point is the bulkhead connection is one of, if not the main harness. Any damage to that and just about anything can fry.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Yeah as Jack and Rick have both said and i tend to think it will be something along the same lines, something there isnt getting good clean current flow. Id pull the side panel off, remove the battery, pull it all apart and check everything in that whole area wiring wize, make sure everything is clean and tight, + and -
Do you have any of these dead ECMs sitting around?? Have you pulled one apart to see if you can see any blown components? If you do have any of them there, check the internals for any signs of a power surge (if youve got more than one there, check them all and if you find anything, see how that bit looks in the other ECMs). Something is killing them to get through that many.
Under the bonnet ubove the cruise servo
Do you have any of these dead ECMs sitting around?? Have you pulled one apart to see if you can see any blown components? If you do have any of them there, check the internals for any signs of a power surge (if youve got more than one there, check them all and if you find anything, see how that bit looks in the other ECMs). Something is killing them to get through that many.
Under the bonnet ubove the cruise servo
Thread Starter
Racer
Joined: Dec 2004
Posts: 470
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From: Phoenix Arizona
Jump started the car once maybe twice in 16+ years. The dealer charged the battery at times when the alternator stops working and the replace the alternator.
I believe your theory is correct as sometimes when the car is started runs very strong other times almost like someone disconnected three plug wires. Yesterday ran an errand hit a bump in the road and the preformance changed for the better, usually it worsens.
I believe your theory is correct as sometimes when the car is started runs very strong other times almost like someone disconnected three plug wires. Yesterday ran an errand hit a bump in the road and the preformance changed for the better, usually it worsens.
Thread Starter
Racer
Joined: Dec 2004
Posts: 470
Likes: 0
From: Phoenix Arizona
When removing the wire from the power tower are they in any particular order, should I label each as they are remove and replace in the indentical sequence? Or does it not matter? And certainly look for traces of battery acid on each connection. 
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
I live in Scottsdale. My AC Delco battery leaked acid down through the cable and through the fusebox (this is a '93). All of the fuses and the inside of the box were coated in white. My problems weren't nearly as crazy as yours, but did effect performance. Trevor down at Exotic Muscle fixed it up for me. I can't remember what I paid, but it was reasonable. You may want to check with him and maybe at least get some advice.
Thread Starter
Racer
Joined: Dec 2004
Posts: 470
Likes: 0
From: Phoenix Arizona
I live in Scottsdale. My AC Delco battery leaked acid down through the cable and through the fusebox (this is a '93). All of the fuses and the inside of the box were coated in white. My problems weren't nearly as crazy as yours, but did effect performance. Trevor down at Exotic Muscle fixed it up for me. I can't remember what I paid, but it was reasonable. You may want to check with him and maybe at least get some advice.
Thanks very much