cold engine/trans p0785 code (no 1st , no overdrive) ok after warmup.

Question

I recently acquired a 1998 Chevy S10 4.3l automatic (4l60e). P0785 code appears only when engine/trans are cold. The ignition switch, A,B, TCC(PWM), and 3-2 downshift solenoid(s) have been replaced and fluid/filter changed. This has greatly improved the shifting, but only after it warms up. Example: In the morning, I start the truck and immediately the check engine light comes on (po785), there is only 2nd and 3rd gear (and reverse). I drive it until it reaches operating temperature(less than 5 minutes). I then pull over and shut the engine off. I wait a few seconds, restart the engine and it drives fine the rest of the day. If I clear the code from the computer, I wont see the check engine light come back on at all until the truck is allowed to get cold again, usually overnight. Next morning its the same thing like clockwork. I should also mention this: The trans will remain stuck in 2nd or 3rd gear, regardless of engine/trans temperature. ONLY after I stop and restart the engine (as described above) will the transmission function properly. Any ideas?

Answer 1

Did you ever find a fix for this?  I have a 97 Tahoe that is doing the same thing