I've never messed with the ECM, never even had to think about it, but lately, every now and then, my check engine light has started flashing. Most of the time it flashes for a minute or two, and the goes out. One time my wife was driving the car and she said it started flashing on the highway, and the car stumbled bad enough that had to pull over and stop it. it started up fine and has ran smooth ever since

no codes were stored

I understand a flashing light could mean something is wrong with the ECM. Years ago I bought a backup, but I have no idea if I bought the right one, or if there is any reason why this one wouldn't work in my car.

My car is a 89 V6 Camaro with a 5 speed. Did I buy the correct one? it does have a PROM and CALPAK installed, I checked

Am I on the right track for finding the problem? I was thinking of swapping computers and see if it happens again

 

HNL comes up as 1986 2.8L manual trans.

It might work, might not.

Pull your ECM down and see if the service number matches, and also application, as in matching trans type.

 

That is the correct ECM and PROM for your car.

When the SES was flashing, was this a rapid flickering? If so that is a sign that the ECM wasn't running from the PROM. This could be due to the PROM needing to be reseated in the socket. Or the PROM itself is starting to lose data.

RBob.

 

I'd call it more of a steady flashing. I used to have a random flickering problem years ago, but a fuel filter change fixed that

Glad to know I have the correct one, I'll probably swap them out and see if that makes the problem better or worse

 

so I don't break anything, can somebody tell me the best way to remove the PROM? It seems stuck and I don't want to force it

 

Use a flat bladed screw driver with the tip under the proms carrier tab. You can use the ecm case for leverage . Gently pry up one side a ways than the other.

 

I finally got around to swapping the computers. The replacement works fine so far, but the problem was intermittent with the last one, so I'll have to drive it a while before I know that the problem was fixed.

Another newbie question... How many of the numbers printed on the ECM matter? Of the photo I posted the first line of numbers matched, the second one didn't, and the third line matched.

I see ECM's for sale that say they will work on my car, and only the top number is the same. they also fit a ton of other cars, like a 1986 cavalier. Is that right? I would think they would be more specific than that, but maybe not

 

as long as the service number matched you are fine

 

good to know... what do the rest of those numbers mean?