Over the past couple of weeks I dropped the M46 transmission from my 88 745T and rebuilt the overdrive and repaired a leaking engine rear main seal.

I replaced the O-rings for the pump, solenoid, and the first one on the relief valve. I put in the new upgraded pistons and seals. Slapped the puppy back together again and popped the transmission back in on Monday. Went for a test drive. Ahhhh, overdrive engages smooth as can be, I had a happy grin on my face! Started my new job on Tuesday (after 5 months of unemployment!) which involves a 40 mile commute, half on the highway. Overdrive worked like a charm! But yesterday on the way home, it stopped working, and this morning it also did not work.

Symptom: Press button. Nothing happens, but the OD light on the dash comes on. I used a test lamp and verified that the solenoid is getting power. It is also making a clicking sound, sounds like it is doing the right thing.

Press button to disengage and for a brief second it feels like the overdrive is engaging, (rpms drop) then back to nothing.

I don't think it is the relay, as the test light showed that power is getting to the solenoid. Parts guy says the solenoids rarely fail. I did verify that it was working when I had it out, and indeed, the overdrive worked just fine for a day and a half.

Any ideas? (um, ideas that don't involve a can of gasoline and a match.....)

-David