I am going to look at an '87 740 GLE wagon, 230K, manual transmission. The car sounds like it is still in pretty good shape. One problem the seller described does concern me, though. He said the OD "works when it wants to." I was initially confused, because I own an '87 240DL with a manual transmission. I simply shift into 5th gear with the shifter. He said his 740 is a 4-speed with OD--a button on the shifter engages it. Is this random popping out something quite serious--like a sign of impending transmission failure? I'm sure my question has been asked before, but so far I haven't found it in the archives.
Thanks in advance for sharing your expertise.
Mike F.

HI Mike -

I am a 240 guy, but this might help anyway. On an automatic, the button on the side of the shifter handle switches the o/d on or off. The default position is NO LIGHT, tranny will automatically engage when conditions are OK.

If it won't go into o/d, and the amber arrow is OFF, it's likely a wiring problem rather than hard parts failing. On the tranny is the o/d solenoid, one wire to it. If the o/d IS engaged, and drops out by itself then there may be something that interrupts the power to the solenoid. Maybe a bad connector onto the solenoid? Maybe the relay (re-solder it anyway). Maybe a wire chafed en route to the tranny.

Good Luck on the car.

Bob

:>)