93 GV: limp transmission

[ptsouris]

My 93 plymouth started this problem about a year ago doing it once a month or so but by now it's a daily thing. It simply refuses to upshift to the last gear. The problem resets when I restart. My mechanic has changed the shift solenoid twice to no avail. He hooks it to a scanner but doesn't tell me what codes come up if any.A couple of times when I restart, the car runs crappy for a while then it's ok. I don't khow if this is related to the tranny problem. I suspect this to be an electronic problem of some sort but good luck finding it, right? anybody have any suggestions?

[RIP]

You can read basic MIL codes in your driveway without a specialised tranny scanner. Cycle the key from off to on/run (not start) 3 times leaving it on. Now watch the number of times the Service Engine/Check Engine light blinks. All codes are 2 digits. A code 12 would be flash, pause, flash, flash. Multiple codes are seperated by a longer pause. Code 55 means the reading has ended. You may not see any codes but it's worth a try.

Are you seeing any speedometer, tachometer, or cruise control problems? I'll assume the fluid/filter have been changed. Any fluid besides ATF 3 or 4 will cause problems.

[ptsouris]

I just did the key dance and discovered 2 codes stored.( 12 and 21). Thank you for showing me how to do that. As far as what type of tranny fluid my mechanic used I will find out tomorrow.What do these codes mean? Thanks again for your time.