96 GA - Every (warning) light in the house is on, but noone's home.

[thetandycollector]

Hello all,

Got a car into the shop today, 1996 Pontiac Grand Am, for resale. This thing is a piece of art, looking at it, it's all like new. But, started it up, fuel and temp read halfway up the scale at cold start, ALL warning lights come on and stay on, including temp and low fuel "dots."

Was going to try to drive this car home, left the shop and it stayed in first until twenty miles per hour, then when it should have shifted instead it bogged down and cut off fuel, like an over rev situation. Let off the pedal, ran like normal, then repeated itself upon accellerating again. Sometimes it misses and pops during accel. Any clues??

Bill - Eagle Automotive

[thephantom1492]

Start with code reading, then I would take a look at the PCM connector for oxydation. Also check up the fuses.

[thetandycollector]

Originally Posted by thephantom1492

Start with code reading, then I would take a look at the PCM connector for oxydation. Also check up the fuses.

All of the connectors are free from oxidation, and have been cleaned/checked. There are several white wires from the computer that have been spliced, but I checked them and they are all routed to the correct components.

Replaced PCM w/salvage unit from an S-10 (part #'s cross), no difference.

All fuses are good, free from oxidation, and the correct amperage.

Checked (because I've had something like this happen before) the ignition switch with a new one I had in stock. No change.

Also noticed the brake/shift interlock has been forcibly disabled. Not sure exactly how, but PRNDL1 doesn't register any gear, and shift release button will not push in, however shifter moves from gear to gear smoothly.

Possibly PCM was replaced before this one and will need flashed unless I can find a unit out of twin 96?

[thephantom1492]

check for codes

[Blue Bowtie]

Yes, the S-10 PCM is likely flashed differently and you're likely running in backup mode. From about '93 on some models and nearly all models by about '96 there are no plug-and-play PCMs unless the vehicle is identical down to the options. Even then, the VIN is different in the programming and some replacements don't like to talk to other modules when that happens.

[thetandycollector]

Originally Posted by Blue Bowtie

Yes, the S-10 PCM is likely flashed differently and you're likely running in backup mode. From about '93 on some models and nearly all models by about '96 there are no plug-and-play PCMs unless the vehicle is identical down to the options. Even then, the VIN is different in the programming and some replacements don't like to talk to other modules when that happens.

To answer a question before I answer this quote: Only one code is present, O2 Heater Circuit High Resistance.

Thank you for the flash info. The old PCM and this one both did the same thing, I figure the guy that we bought it from assumed it was "plug n' play" (thank you for the Windows 95 coined term), but found that it was more like MS-DOS: Install the drivers and bite your nails while booting hoping you coded the batchfile right LOL.

I wasn't sure about the flashing because I get mixed info from all sources I have talked to. I'll get the original PCM flashed and see what happens from there. Thanks for the assistance!