95 sse Bonneville n/a. Drives poorly. Stakes off in second gear. Idle rough has voltage Spikes and computer registered low low transmission temperature.
codes are 1640 1650 and p0712

After some research I’d realized these ecu’* are a common failure part. I do have a new one coming and I’m aware I have to swap over the prom chip.

The



car has a recent run up newer egr and new alternator. I did remove the computer to inspect it. I cleaned it up a bit and the car ran great for a day then starting acting up again.

has anyone dealt with this situation ? Any suggestions would be great.

Check the wiring harness going to the tranny.

What is the voltage, measured by a digital volt/ohm meter, at the battery posts when it is idling?