I had the tranny rebuilt in my 1995 cutlass supreme. ( It was slipping and making whining noise) I was able to drive it 2 days before it quite shifting down to 1st or 2nd. It starts off in 3rd gear and will go into overdrive. The tranny shop tells me they checked the obd for codes and that there were some but they cant get the computer to erase so they can drive and see what new codes come up. They put in a used comp ad now the car wont start. Are these computers re-programmable? or am I stuck with buying a new comp. Im already 2200 into this and a new gm computer is about 400. Help please.

Was the transmission doing the same thing before you had it rebuilt? If it is the computer I would save yourself some cash and get a used one from the wrecking yard and have it programmed to your car. To get it programmed your either going to take it "the whole car" to the dealer and pay them to program it or send the PCM to a aftermarket programmer and have it flashed to your car. It'* kind of hard to diagnose something third party. Is this shop reputable?

"There were some codes".

It would be really helpful to know what those codes were. Makes me even wonder if they have the proper scanner to scan the OBD 1.5 systems.

sounds like to me too they dont have the right tool for your car