Tank91RS

Ok i just did the ol' paper clip trick to pull my Diagnostic Codes to figure out why my Check Engine Light is on.

I got code 51 which i think means eaither my ECM is bad or PROM isnt calibrated right. Any ways to eliminate one or the other?

And how easy of a fix would these be for a 17 yr old. (affordable is more what i mean)

haps

iTrader: (4)

In my many attempts to diagnose my primary coolant fan problem, my car threw a code 51. I replaced the ECM($60) with the stock EPROM and it solved my problem. Like you I didn't know which one it was, so I gambled.

Tank91RS

Hmm, if my cooling fan is hooked up to a toggle switch..could that throw the code? Just since its a change that the computer isnt use to?

haps

iTrader: (4)

I suppose anything is possible.

Tank91RS

Well. How would i go about changing out my ECM?

haps

iTrader: (4)

Passenger side floor board area under the dash. Pull it out, remove the plugs, take it up to a reputable parts store that has a replacement. Pull out the EPROM and put it in the new one, the parts store will more than likely take your old one as a core. Reinstall. 20min at most.


**Edit, BTW, better make sure you understand why your old ECM is faulty/shorted, otherwise, you might end up with the same result when you plug in the new one. That switch may have something to do with it. Also better disconnect the neg battery terminal before removing the old and installing the new.**

Tank91RS

ok..well replacing sounds easy, but isnt there alot of reasons for one to go bad?
how would i track that down?

86ttopbird

From what I have heard, GM had a bad round of ECM's in certain years. They just go for some reason. Also it is pretty rare that the PROM goes out but it is possible. Replacing the ECM is easy. First disconnect the negative battery cable and make sure it is not touching any metal. Then take out the three 7mm screws that are holding the passenger side hush panel on and take it down out of your way. Then there will be 2 more 7mm screws holding the ECM bracket to the dash. Remove the plugs, then take out the screws and pull the ECM down out of its resting place. There will be a cover on top of the ECM secured with two 1/4 inch screws. Take these out and remove the cover. This cover usually is stuck in place so you will need to CAREFULLY pry it off with a screw driver. Next you should see the MEMCAL. This is characterized by its blue housing. There will be two latches, one on either side of it. All you do is push both of these outward with your thumbs at the same time and the MEMCAL will pop out. Next take your MEMCAL and put it into the new ECM. Make sure the slots on the bottom of it are lined up properly and just push down on both ends of it until you hear two clicks. That would be the latches popping into place. DO NOT FORCE IT!!! Next place that little PROM cover back on and put the 1/4 inch screws back in. Next remove the nuts that secure the old ECM to the mounting bracket. There should be 4 of them and they are 10mm i believe. Take your old ECM off the bracket and remove those threaded stud clips and put them on your new ECM in the same location as the old one. Put your new ECM back on the bracket and replace the nuts. Next put the ECM back up into its resting place and replace the 7mm screws that hold it there. Put the plugs back in and then replace the hush panel. Re connect the negative battery cable and start the car. Now once it is running, you need to do an idle re-learn procedure. This is simple. Put the car in drive with your foot on the brake obviously and just sit there like that until the cooling fan comes on then shut the engine off. Wait 30 seconds, restart the engine and repeat the procedure, then shut it off again. Wait another 30 seconds and then go for a drive. Now you can let it relearn by driving it around a bit but it will run funky until the ECM learns how to control the idle and puts its keep alive tables into place. Hope this helps!!

Tank91RS

Your amazing! Thanks this really helps!
ECM is ordered and on its way, I'm hoping to have it by this friday for replacement, and hopefully my car will be up and read to rumble.

I'll let ya'll know how it turns out.

Tank91RS

Ok, so not good guys.
I removed the panel and saw the ECM,
was like ok try and find the screws to let it out, and i go to grab it and it just falls into my hand.

Should it be on a bracket or something so it doesnt move lose while driving?

Tank91RS

and ive done a little searching and think that my model doesnt come with more stuff attached to it, therefore being, less work to get to it. Hes the pic of it and where it was sitting.

86ttopbird

Thats the newer style ECM bracket. That plastic tongue sticking out locks around the middle of your ECM. Once you push your new ECM up into the bracket, that tongue will lock around the middle of it holding it there. Then when you put the hush panel back on, the ECM will not go anywhere.

Tank91RS

ok so my installation should be just hook up the wired to back and snap it back in place?
then do the idle re-learn thing?

Went to plug-in my new ECM, stoped right before because i felt a soft spot on the device. Read the label and it says... " Warning: You must remove PROM(s)/CALPACK from the original computer and istalll in replacement computer view installation instructions for details."
and behind this little sticker was this hold (in attached picture) now... im pretty sure my PROM goes there...if only i had one to place it there...
" Note" Missing, misinstalled, defective, or incrrect PROMS/CALPACK may cause multiple trouble codes, poor performance, unusable diagnostics, or contant check engine light.

And now heres the kicker.. the ECM i removed wasnt the original. the PO must of replaced it, im assuming... Soo now i think im missing a PROM or need help finding what goes there.

KC88GTA

You appear to have what is needed pre-installed for you, wish mine had that!

1) Prom [the larger IC] on the right of photo is there, you have no memcal
2) Calibration [calpack] smaller IC on the right is also there

Ask ask around but, I believe you are ready to [plug-n-play] ! Just disconnect battery, reinstall new ECM, reconnect Battery, start car to re-learn, idle, off, idle, drive

Check for error codes before driving, but looks like you got prom/package pre-installed in ECM for you, Mr. Lucky! I'm still looking for Prom/Package to plug -into ECM for my 88GTA, mine has memcal, yours appearently does not.

RBob

iTrader: (1)

You do need a PROM for the replacement ECM. Check your original ECM for the PROM and move it over to the new ECM. On the '8746 ECMs the CALPAK is soldered in, so only the PROM needs to be moved over.

If the original ECM you took out didn't/doesn't have one then that is why the code 51. Although this will also cause a rapidly flashing SES light.

There are pictures of the various pieces in a thread in the sticky's.

RBob.

Tank91RS

I don't have the Original ECM, the one i removed was the one the PO put in. So now im on the hunt for a PROM.

Could that cause a really bad electical drain? Not having a PROM installed?

Well the computer is in, but the check engine light is still flashing, im not sure if it is draining though, as i haven't driven it much. But the battery was at around 11v. And when i flipped my fan's toggle switch it dropped down to 10v.

Should that happen?

8bluebird7

Is the ECM located in the same place (Passenger side floor board area under the dash) on all third gens? (87 Firebird in particular)

Tank91RS

Im pretty sure it is, not possitive. But if you look under there and see 10mm screw heads then your chances are its under there.

I know my 91 camaro doesnt have a Glovebox under there so thats how i figured it was there. Firebirds might. im not sure.

98t595

what are the sticky's where and what are they on here seen this alot... people saying check the stick's ok........... where lol

RBob

iTrader: (1)

Sticky's are the threads listed at the top of the board. There are sticky threads listed then normal threads listed. Being sticky they don't drop off as they become older.

RBob.