ECU CPU electrical problem on 99 SSEI help needed
 

Well all of a sudden while I am driving my 99 SSEI my guages act as if I am just starting the car. Anotherwords they will max out, return to 0 and then go to the actual reading. I brought the car into the mechanic and they said it was a computer problem and I have to take the car into the dealer.

Now before I go to the dealer and drop some serious cash I was wondering a couple of things

1- Is it a cpu problem as diagnosed?
2- Can I just get another cpu and exchange it?
3- What cpus would be compatible with mine (different years or models)?
4-Can I get a cpu from intense racing?

Thanks in advance, Jack

The PCM has no control of the gauge 'sweep' funtion. That's built into the cluster. I'd suggest following the Techinfo instructions for removing your instrument cluster. Clean the contacts, and put it back. That fixes these types of problems 90% of the time.

And find another mechanic ;)

i had the same problem with mine. but it turned out that the + terminal on the battery was leaking acid and eventually fell off. sounds dumb, but it's true

This same thing happened to my 1999 SSEi shortly after I bought it. Check to make sure the battery connections are tight, and not leaking. You might also try loosening the terminals to make sure the bolt into the battery isn't corroded in place. Acid will do this if it's leaking and you don't catch it soon enough.
It was a major pain for me -I had to cut the battery cable and put a new terminal on.
I wonder if all 1998 & 1999 Bonneville SSEi (any 1998 and 1999 owners for that matter) should check this out and if it's a problem with more than say, 10, a report should be made to GM. This is, only if the original battery is still in the car.
BTW, the exact same thing happened to my friends 1999 Regal LS. The original battery had the positive terminal leaking acid and I replaced the battery for him back in January, and the car only had around 70k on it.

Update:

Thanks for all the replies.

The problem is getting worse and I brought it to a repair shop and they say it is a problem with the cpu therefore there are no error codes coming up. And when the gauges do their crazy thing I also lose my ABS brakes because the pedal gets weird. And now it is to the point where the car wants to cut out when before the gauges would just max out. Now with this problem getting worse I want to think it is more of a charging issue then a cpu issue and the last thing I want to do is bring this car into the dealer. Also the car would not react properly when using my remote to lock or unlock the doors. It was as if the car did not have enough power to do so and it was struggling. Any help would be appreciated.

Thanks, Jack

How old is your battery and alternator?

The PCM has no control over your ABS. That's a seperate module. Find another shop.

I am not the original owner of the car but I assume the battery and alternator is original. As far as the ABS is concerned I feel that it is being affected by some underlying problem.

Thanks, Jack

An electrical check is definitely something you'll want to do, and if either the battery or alternator is weak, replace BOTH at the same time.

Yup, that's what I was getting at... :wink: