I have been invited to assist my grandson diagnose the transmission reverse issue with his newly purchased '02 (140k miles). The previous owner was having reverse problems to the point that he decided to sell an otherwise excellent car. He was the first owner and never had the ATF changed. He had the ATF changed as a result of the issue but that did nothing to affect the failing reverse. It worked fine when first driven, no slipping, acted normal. Shortly it began to fail to engage and now does not engage at all. It is not in reverse and just slipping.
He did buy at a price assuming replacing the trans so we are not real disappointed.
I am familiar with the ZF transmissions of that era and have full documentation on them. I know that the shift lever is a switch operating a solenoid on the bottom of the transmission under control of the Trans Control Module.
What is the probability of repair short of replacing the trans?
No CEL codes but understand that my reader will not read trans codes
Most likely problems in order?
Worth having a dealer read any trans codes?
Which solenoid engages Reverse?
Any links to trans documentation?
Thanks for your help!