'88 635csi Transmission problems, limp-home mode

[walczyk]

So the dreaded limp-home mode happened last year to my father's 635csi, and he has two spare non-running cars, so I replaced the tranny and the TCU. I let it sit there for eight months til now when I finally put the exhaust back in and filled it up with oil. The problem persists! I am *not* sure how much oil is in the transmission now, I guess it could be low. I've been looking online for advice and potential problems, and I found a couple things like electrical connections. Perhaps the accelerator is corroded and isn't giving a good signal to the TCU, but I hear if you put it in 3-2-1 mode the car will upshift and whatnot. Where else can I look for a fault? I would kill for a diagnostics tool, but those seem impossible to find. I have a wiring diagram manual for the car, but I'm not sure how to even begin to fault trace this. I guess it could be the tranny if the fluid is an issue, I put in about 7 quarts (it had been draining for a very long time), but ignoring this, where else should I look?

[mauryc]

Get the ETM for 1988 and troubleshoot it by the book - fool proof. Cross each possible culprit off one by one. Guessing doesn't help. I fought a transmission issue in my 88 for a year. It wouldn't shift out of first unless it was in 123. I replaced everything including rebuilding the valve body. I was vacuuming carpet by the accelerator and - just for fun, tried to push down the trand kickdown under the pedal and it was stuck. Unpluged the wire and all was better. Replaced the kicktown fom one from an e30. $5. How embarassing.

Maury

[walczyk]

Wow can't believe I spent this long without fixing it. It was the ECU all along!!! The damn fuel rate gauge stopped getting the right signal from the ECU, and boom it wasn't working. Can't believe I didn't just attempt to fix this 4 years ago. For fuck's sake.