96 Sable, Speedo drops to 0, OD Off light flashes

[sandiegodude]

Hi guys.

I've got a gremlin running around in my electrical system that is absolutely driving me crazy.

After about 15 to 20 minutes of driving, no matter the temperature of the engine, no matter how I'm driving, no matter if its city or freeway, the speedometer drops to 0, the Odo stops spinning, the Overdrive Off light begins to flash (If the car actually shifts into overdrive, otherwise it won't happen) and performance gets really bad. The engine knocks like its running super lean and the car will shift at 2000 RPM into the next higher gear, making acceleration almost impossible from a complete stop, as the super low shifts coupled with the super lean condition robs the car of almost all power. This happens for about 5 minutes or so, then the car "wakes up", the speedo goes back to normal, the odo begins to spin again and the overdrive off light stops flashing. The car will behave itself afterwards, although once on a long drive it happened a second time. There is several times where the car will "wake up" for a moment, the speedo will pop up to the correct speed, then drop back to zero again, and I end up having to wait another 5 minutes or so for it to wake up.

Obviously this has really limited my range as far as driving, mostly to work and back. Outside of that, the engine and transmission performs just fine, acceration is good, no knocking, no pinging and no other issues.

I'm thinking the culprit is the ECU, but I have no way to be sure if its that, or something else. Has anybody else seen this before? If so, what did you do to fix it?

Thanks!

[rhandwor]

Go to Auto Zone or Advanced auto and check for codes its a free service.
Then reply with the codes.