How difficult is to replace ECM?

[sebaz]

I took my 94 Buick LeSabre to a mechanic after it cut off on me about 25 times in 6 miles. This happens only in the morning after a coldish night (55 or so), because after 3 PM or so the car runs fine. Also, starting it is very difficult in the morning, but in the afternoon it's not so hard. So these guys are telling me that they would need to replace the alternator (which was replaced about one year ago) because it's only producing 12 volts when it's supposed to do 14, and the Electronic Control Module, and they wanted to charge me close to a thousand bucks for that. So I said no thanks and brought it back. My questions are:

1) Does it plausible to you that the problem could be in those two components, when it's clearly temperature related? The colder it is the more difficult to get it started, and the more it will cut off when running.

2) I know replacing the alternator is easy, but what about the ECM? I read about it in the Chilton manual, and information on it is not very detailed. Also, these guys told me they need to replace the EPROM, which needs to be reprogrammed, something I also read in the Chilton manual, but it gets more complicated, because it says there that depending on the car there may be an EEPROM, a KS, or a MEM-CAL. How do I know which one mine has? If I manage to replace the ECM plus the EPROM or whatever it is, do I need to still take it to a dealership so they reprogram the EPROM, or is it not necessary for this model.

I would like to give this car one more chance before taking it to the junk yard, because as it is, I don't have a thousand bucks to fix it, and at this point I spent about $1500 in repairs, plus $3000 for the car itself, which needless to say was the worst deal of my life. So I would really appreciatte any help on this.

Sebastian

[spinne1]

If by ECM you mean the car's computer, it is a pretty easy fix. You first get one from a boneyard (or buy one from a parts store), then remove the black plastic shield below the dash (7mm socket works great, or a torx screwdriver (don't remember the size). Now, look under the dash by the passenger's feet and look for the silver box with the three main wiring harnesses connected to it. It is held it place by a small metal bracket with a single 10mm nut. Remove the nut and the bracket and you can wiggle the computer out. To remove the wiring harnesses, squeeze the plastic on the sides of the harnesses to release the locking mechanisms and pull away from the computer. After the computer is out, use your same torx screwdriver to remove the cover plate on your computer, under which the chip resides that you need to replace with the chip in your car's computer (I think the 94 still uses the replaceable chips rather than requiring a reprogram). Then put the cover back on, stick the computer back where you got it, reconnect the wiring harnesses, and reattach the bracket with the 10mm nut. Then test the car before putting the black shield back on in case you find it doesn't work right or needs further diagnosis.

It's about a 1/2 - 1 hour job.

[Andrewhuffman]

it took me 10 minuts to swich mine.... on a 95 lesabre.

[sebaz]

Are you sure it's in that location? Because according to the Chilton manual it should be there, but when I open the hood I see a thing on the right side close to the brake master cylinder which looks like the computer, and actually the Chilton manual says that is the position for cars starting 1996. I know mine is a 94, but also a 94 is supposed to have an OBD I connector and this one has an OBD II. But I'll check the location tomorrow, because I really never looked under the dashboard. It might be that what I think is the computer is something else.

Originally Posted by spinne1

If by ECM you mean the car's computer, it is a pretty easy fix. You first get one from a boneyard (or buy one from a parts store), then remove the black plastic shield below the dash (7mm socket works great, or a torx screwdriver (don't remember the size). Now, look under the dash by the passenger's feet and look for the silver box with the three main wiring harnesses connected to it. It is held it place by a small metal bracket with a single 10mm nut. Remove the nut and the bracket and you can wiggle the computer out. To remove the wiring harnesses, squeeze the plastic on the sides of the harnesses to release the locking mechanisms and pull away from the computer. After the computer is out, use your same torx screwdriver to remove the cover plate on your computer, under which the chip resides that you need to replace with the chip in your car's computer (I think the 94 still uses the replaceable chips rather than requiring a reprogram). Then put the cover back on, stick the computer back where you got it, reconnect the wiring harnesses, and reattach the bracket with the 10mm nut. Then test the car before putting the black shield back on in case you find it doesn't work right or needs further diagnosis.

It's about a 1/2 - 1 hour job.

[spinne1]

Originally Posted by sebaz

Are you sure it's in that location? Because according to the Chilton manual it should be there, but when I open the hood I see a thing on the right side close to the brake master cylinder which looks like the computer, and actually the Chilton manual says that is the position for cars starting 1996. I know mine is a 94, but also a 94 is supposed to have an OBD I connector and this one has an OBD II. But I'll check the location tomorrow, because I really never looked under the dashboard. It might be that what I think is the computer is something else.

Maybe you have some Franken-car prototype that slipped out of the GM labs. I don't think 94s have the computer under the hood. Take a photo and post it if you can of the thing under the hood. I'm curious.

[Bassasasin]

WAIT WAIT>... get that alternator fixed first... the PCM may not be bad at all..

BASS...

[Andrewhuffman]

the computer under the hood next to the master cilider attached to the inside of the front left finder wall is the ABS computer.

[Bassasasin]

The PCM is behind the glove compartment.
You have to remove the kick panel passenger side to see it. It is tucked kindof high in there.

Good luck.

[Bassasasin]

Alternators are running (I paid) about 70 bucks at a parts store. PCMs are about 100 rebuilt...
So figure you may best find another Mechanic.

Good LUCK.

[Andrewhuffman]

i paid 10$ for a working ECM form the junk yard. i got lucky and it had the same part nnumber. if its the same one your lookin for, i can mail it to you for 20$ via paypal, money order or Personal Check. what number is on your ECM

[sebaz]

Originally Posted by Andrewhuffman

the computer under the hood next to the master cilider attached to the inside of the front left finder wall is the ABS computer.

Ohhh. Excelllent. So my car isn't a weird GM prototype after all. That's good news. I'll check into it as soon as I can. Thanks for the info.

[sebaz]

Originally Posted by Bassasasin

WAIT WAIT>... get that alternator fixed first... the PCM may not be bad at all..

BASS...

Yea. I'll do that, however, this problem started around October of last year, when the alternator was only about 3 months old. Also, I read in the Chilton manual that if the computer is bad then the car defaults to some set of basic values that are far from optimal, and it affects performance a lot. So that might be true since this car used to give me about 370 miles per tank and now it only gives about 260, a huge drop. Could it be that because the computer is bad the car is running on open loop all the time and that's the reason the gas mileage is so poor?

Sebastian

[MT-2500]

Originally Posted by sebaz

Yea. I'll do that, however, this problem started around October of last year, when the alternator was only about 3 months old. Also, I read in the Chilton manual that if the computer is bad then the car defaults to some set of basic values that are far from optimal, and it affects performance a lot. So that might be true since this car used to give me about 370 miles per tank and now it only gives about 260, a huge drop. Could it be that because the computer is bad the car is running on open loop all the time and that's the reason the gas mileage is so poor?

Sebastian

Have you check for codes?
You need to pitch that chilton in the trash can and get you some real info.
Like a factory service manual or .
http://www.alldata.com/products/diy/index.html
MT

[sebaz]

Originally Posted by MT-2500

Have you check for codes?
You need to pitch that chilton in the trash can and get you some real info.
Like a factory service manual or .
http://www.alldata.com/products/diy/index.html
MT

I checked for codes but it doesn't give any, which is probably a sign that the computer is broken.
A factory service manual I think it's very expensive, as for that website, I'll check it out. Thanks.

[sebaz]

Originally Posted by Andrewhuffman

it took me 10 minuts to swich mine.... on a 95 lesabre.

Which kind of chip does yours have? Mem-cal, PROM or KS? I'm asking because I'm searching the Ac Delco catalog online, and I type in mem-cal and nothing comes up. Then I type KS and nothing comes up. Finally I type Prom and two results come up, 16202842 and 216-115, both with the description "EPROM, PCM". Since I had already specified which vehicle I have, then I guess mine has an EPROM. So that leads me to a few other questions:

1) Do all of these EPROMs need to be reprogrammed, or some do and some don't?

2) If it's a chip with values (as ROM, Read Only Memory indicates) then why does it need to be reprogrammed at all? I mean can't I just swap it from the old computer to the new one and that's it?

3) If I don't have a choice but to have it reprogrammed, can I just take the chip to a Buick dealership and pay them just for that, or do I have to have them do the whole computer and EPROM replacement and reprogramming there?

Thanks