'94 LeSabre with "issues"

[SrBenelli]

Hey all. Our '94 Buick LeSabre has a few "issues" that my all be related.
First, the "Battery light" remains lit most of the time. After troubleshooting the entire charging system, a shop determined the cause was a bad ECM.........car ran fine otherwise.
While waiting to change out the ECM, two more problems developed. The "Check Engine light" started to come on, accompanied by a high idle speed. Also, my speedometer quit working at the same time.
Now, I seem to recall that the speedo worksbygetting asignal from the VSS via the ECM.
Could all of these problems be a funky ECM?
Thanks
Steve

[Flatrater]

YES and YES!!!!!

[SrBenelli]

Thanks for the reply.
Car is a 1994 LeSabre with the "3800 series" V-6.
Can't pull troublecodes because this particular LeSabre has the "16 pin" port (OBD II style) as opposed to the older 12 pin port.....and as far as I'm aware, you can't just "ground out" the 16 pin ports to flash troublecodes like the 12 pin ports.
As I said above....the ECM was already suspect (with the "battery" light periodicly lighting). The "Check engine" light began to come on and off (with no apparent drivability symtom). After aday or so, the light remained lit (constant on) while driving, with an abnormally high idle. Within a day or so after that, the speedometer (anolog style) quit working.
Now......I *COULD* have a bad throttle position sensor....*AND* a bad VSS.....*AND* a bad ECM....
....but for everything to "act up" at pretty much the same time is quite a coincidence (and the car has relatively low milage too...less than 60K). The "common denominator" seems to be the ECM.....all of the problems *COULD* be ECM-related all on their own. And for so many systems to be having problems.....I'm thinking the ECM is my problem.

Thanks
Steve

[SrBenelli]

btt^^^

[Flatrater]

Yes all your problems could be caused by a bad ECM but you have to remember that a bad sensor can bring down the ECM causing your other problems. Their is no easy way to be sure all you can do is try a new ECM and go from there.

[SrBenelli]

Originally Posted by Flatrater

Their is no easy way to be sure all you can do is try a new ECM and go from there.

Ok.....'nother question. According to Haynes (they suck, by the way lol), '93 and older LeSabres were equipped with an ECM under the dash. '96 and newer cars had a PCM located under the hood. That leaves '94 and '95 model years in question.
As I posted above, my car has a 16 pin diagnostic port under the dash (OBD II style). Also under the dash is what I believe to be an ECM....but it's a sealed unit (without the "door" for the PROM chip).
So.....what the hell do I have??? ECM? PCM?
On a decal on the "mysterious silver box under the dash" ( ), reads:

SERVICE#
16176558
*AI3430K533518957*
------------------------
16193430
*AI3430K533518957*

Any ideas?

Thanks
Steve

[Flatrater]

Out of memory the 94 was still an ECM and most of the 95 were also an ECM. usually only the computers mounted under the hood are programmable. Having the 16 pin DLC and not the underhood PCm means it was a hybrid car not fully OBD 1 or OBD 2.

Do you have 3 electircal harness on your ECM? Are the plugs red, white and blue? If they are the same colors than it has a prom.

[SrBenelli]

Originally Posted by Flatrater

Out of memory the 94 was still an ECM and most of the 95 were also an ECM. usually only the computers mounted under the hood are programmable. Having the 16 pin DLC and not the underhood PCm means it was a hybrid car not fully OBD 1 or OBD 2.

Do you have 3 electircal harness on your ECM? Are the plugs red, white and blue? If they are the same colors than it has a prom.

From memory (until I go outside and double-check), there's only ONE harness. It travels around from the passenger side, wraps around the ECM (?) and plugs into the bottom. The plug is either yellow or blue (I remember seeing both colors there) with an orange "locking tab" securing it.

Thanks

[SrBenelli]

Originally Posted by SrBenelli

From memory (until I go outside and double-check), there's only ONE harness. It travels around from the passenger side, wraps around the ECM (?) and plugs into the bottom. The plug is either yellow or blue (I remember seeing both colors there) with an orange "locking tab" securing it.

Thanks

OK.....disregard the above. Wrong "mysterious silver box". I located the "proper" one with the red, white & blue connectors......part # on it reads:
SERVICE#
16183247
------------------------
Oddly enough....when I pulled the unit down (didn't un-couple it...just let it down to "floor level", dangling by it's harnesses, my speedo mysteriously started working again (on the drive to the parts store) ....the return trip? Speedo dead again.

Now, I called the dealer to get some more info and they *STILL* refer to the unit as a PCM.....not ECM. (aparently, the 94 & 95 model years are "oddball" years in between). Dealer also quoted me a price of $250-somthing for it.
Went to my local auto parts store to see if they have a better price....and aparently, they need to special-order it.......still waiting for a price from them.

[ottoracefan]

Originally Posted by SrBenelli

OK.....disregard the above. Wrong "mysterious silver box". I located the "proper" one with the red, white & blue connectors......part # on it reads:
SERVICE#
16183247
------------------------
Dealer also quoted me a price of $250-somthing for it.
Went to my local auto parts store to see if they have a better price....and aparently, they need to special-order it.......still waiting for a price from them.

http://www.gmpartsdirect.com

I think you might like their price better............

[SrBenelli]

Update.....
Bought a replacement ECM from the local AdvanceAuto for $99. 5 minutes to disconnect the battery and swap out ECM's......
.....and the car's working like a champ!

Thanks y'all!