Hello everyone. I was wondering if you guys could tell me what the signs that the overdrive on my 1980 240 DL (B21F, M46) is going out. Because when ever I try putting it into overdrive it won't go, or sometimes it will but i is real touchy. Like whenever I go over a bumb it wil become diengaged. so please tell me whats the matter here.
Thank you all in advance.
Ian Schilf 1980 240 DL
ischilf@yahoo.com

The going over a bump is the major clue. The 4th gear switch on the right side of the trans. It is in series with the solenoid. Try this while sitting still, engine off.

Ignition on, engine off, in 4th gear. Slide switch, then get under the car and check for votage at the solenoid. While under there wiggle the shift ( or have someone else do it) and see if voltage drops out at the solenoid. While under there, check for loose corroded terminals and broken wires at the connection to the terminal. Sometimes the insulation is all that is holding the wires together.

Further troubleshooting guide available.

Duane

An OD low on tranny fluid will behave this way. So will one with a worn 4th gear switch.

i found, when i had the shift boot off to change my tranny, that the overdrive wires had been worn through by the metal lip around the shifter opening. fixe up the bare wire & seem to have eliminated all my OD gremlins, of course the usual solution on the board here is to re-solder the OD relay. judging by the age of your car, i would certainly unbolt & lift the boot up to check.
good luck
--
-- '82 245GL, B23E, K-cam, under restoration, 350k km --

Most likely this is an electrical problem, not mechanical. On an '80, you have the slide switch in the knob, not the pushbutton, I think -- right?

The troubleshooting approach might be slightly different depending...
--
Don Foster (near Cape Cod, MA)

Hel;lo, and thank you. Yes i do have the switch (slider) in the shift knob.