johnk14

Hi,

I recently had a rebuilt 91 auto tranny put into my 91 Passat. I read that the TCU (transmission control unit) needs to be restored to its basic setting. I don't think that the guy who installed it knows much about VWs...but he was the cheapest. Also, when I shift into drive, it hesitates for about 2-3 seconds before kicking in. Any thoughts? Thanks.

John

boschmann

I've heard lots of gripes about these transmissions & controllers. If you replace the TCM there is an adaption process that should be done with a VAG scanner or simulator like a VAG-COM, but as I recall it really only affects the downshift point & shouldn't be necessary if you didn't replace the TCM. I have seen a similar thing on the B3 Passats where you turn the ignition on & hold the gas to the floor for five seconds then release & turn off the ignition, but don't know if that's compatible with your car. First I'd make sure the fluid level is correct, hot & idling in park then you can scan for codes using above scanners. Finally it is common for the wiring harness where it enters the transmission to fail. It's actuall fairly easy to install (only have to remove the pan & filter) & a updated version is available from VW.

johnk14

thanks for your advise boschmann. I have one follow up question...does the 2-3 second delay for the tranny to engage have any thing to do with the wiring harness? Thanks again for your reply.

Cheers,
John

boschmann

Normally the wiring harness will cause extended or harsh shifts or loss of overdrive, but I cannot say whether it's related or not. The delay to engage is more typical of low fluid. Unfortunately, I'm not that good with internal trans problems. Have you tried scanning it for codes? I do know the harness is a common failure.