All,

New to this forum and fairly new to the Corvette world. I purchased my red 1992, low mileage, C4 coupe last year. Have enjoyed it very much!

My wife was driving it home from church about a month ago and the thing just died. I showed up on the scene but could not get it started. It would crank, just wouldn't start. Had it towed to a local shop. They checked it out. Originally they were able to start it, but then the service light came on. With a dianostic check, they determined that the electrical system had a bad ECM computer.

Trying to find one of these ECMs was like finding a needle in a haystack. Originally, they thought they had a supplier that would send them one, but then he decided he wanted to keep it on hand just in case he needed it. Then they felt like they would have to puchase new from GM. GM kept pushing the build date back every few days until this little breakdown turned into a month long wait. I finally asked the shop to look at other avenues. They were able to find a used one out of a totaled Vette. The shop said the price of the used one would be the same as a new one, but I would probably save a couple of hunderd dollars because they wouldn't have to program it to my car specs- not sure about this one. In the end, I just wanted to car back- told them to go with the used one.

Got the car back today. Price of this ECM $515 + $380 for labor.

One last thing- This car does have an aftermarket, very nice, Clifford alarm system on it (remote start not hooked up). The shop said that there is a technical service bulletin that says an aftermarket should not be put on the car. The shop felt this may have caused the ECM to burn out.

Just some hindsight questions:

1. Does this seem pricey for this type of problem?

2. I know the car is almost 20 years old, but is it really that hard to come by this type of part. Seriously, there are quite a few of these cars out there- I would think it would be a little easier to find one in a reasonable period of time.

3. Anyone familiar with the aftermarket alarm bulletin? It seems like a lot of folks have aftermarket alarms on their C4s.

4. New vs. used ECM. Seems like I could get a used one for cheaper. That's the way most other things work in this world.

Let me know your thoughts. Thanks.

 

Swapping the ECM is a 10 min job, I assume the cost is for the shop's fault finding and diagnostics

Last time a new ECM for a '92 /'93 was available from GM about '02
Only current choices if you need a replacement are used at whatever price the seller wants or rebuilt exchange ( $350+ ish ) and many have had problems with the rebuilt units
Did you get the old ECM back ; could be worth $$$ as a core for rebuilding given their rarity

the ECM in your car does not need programming ( new or used ).
You just remove the chip from your old computer and insert it into the new one ;5 min job which retains the programming you originally had

 

Here is a link to the correct ECM currently listed on ebay. As rodj mentioned installation takes less than 15 minutes including the EEPROM swap. By all means insist on retaining the old ECM as they are in great demand by rebuilders.

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

I am not aware of any service bulletin that specifically addresses the alarm issue, but it is common practice for vehicle manufacturers to advise against any non factory modification that could impact vehicle reliability, performance or emissions.
I would contact the manufacturer of the alarm system for advice. Of greater concern to me would be the installer, it is incredible how bad they can butcher the wiring during installation.

 

What else did they "parts swap" to make it run as well?

Want to save a ton of money the next time? Buy a factory service manual - about $100
If anything you can hand it to the mechanic and tell them - please follow the troubleshooting steps in this manual before you replace anything.

FYI - most of the time your problem is fixed by replacing coil, icm or both. Sometimes its the wire harness from the opti. Rarely is it the ECM.

As a 92 owner I'm still looking for an excellent rebuilder of ECM's. And I have a spare on the shelf. No its not for sale at any price - its very helpful when the troubleshooting tree says "its the ecm or X", 5 min swap of the ECM and I can eliminate it as an issue.

 

The shop did'nt fix anything....they just changed parts until it started. Their bill was twice what it should have been...really.

Spend $75 on a set of used manuals (GM) on e-bay and learn the car. You could have done this yourself in a Saturday afternoon and it probably was'nt ECM related.

And your car comes with a damn fine anti-theft system thats rarely been beat. 99% of all Corvettes stolen since 1986 were towed or a second set of keys was used. An aftermarket alarm is a waste of money IMO. Just a noise maker that everyone ignores, and fills some junk shops pockets. If anything, most of these alarms ARE installed wrong and DO cause problems with the basic operation of a complicated electrical system. Don't let morons work on a space shuttle...

Join a local Corvette club and see who they use for service if you are not interested in home repair & maint. They would know who is honest and who can actually diagnose a problem instead of throwing YOUR money at it until it runs...
...runs long enough to get out of their driveway..

 

Got to laugh at this in a way, no wonder these cores are so rare. Like you I keep a known good spare on hand. We are part of the problem.

 

Thanks for all of the input. I knew I would be sick after posting this! Somtimes the truth hurts! By my very nature, I am "do-it yourselfer", however, I will admit that this car intimidated me a bit because of the perceived complexity. I guess you live and learn!

 

Lots of good people here who are always glad to help. When your finances recover from this disaster, pick up a factory service manual, with that on hand those here can usually get you through any crisis.

 

In addition to the FSM buy a copy of Corvette Fuel Injection by Probst. Very easy read which will bring you way up the learning curve.

 

I didn't pick a copy of this up until I had my Car and FSM set for 4 years.

Despite the trepidation of working on a computer controlled fuel injection car with these, this forum and a couple others - a good set of jackstands, tools and jack you can repair most anything on these cars.

 

Howell automotive has a great book on the tpi systems, also. I think I bought mine at Mid America.