I took the OD relay out of my 84 240 with a manual transmission (M46) and want to re-solder the connections as suggested. However, there are a lot of solder points. Which ones should I redo? Just to make sure that I have the right relay, its blue and about 1x1x3 inches. On the inside there is a small circuit with a chip. The part number 1 259 750 89 63 26. I don't have the Bentley manual yet.
Thanks,
-Steve
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1986 745 w/ M46 200K since new, 1995 965 104K

Actually, your problem most likely lies elsewhere. Relays for the manual trannies rarely fail, where the automatic tranny relays drop like flies after a frost.

The key to your problem, whatever that is, is in the reaction of the dash light.

If the dash light illuminates when you push the button on the shifter, the relay is OK and your OD not engaging is caused by something else.

IF the dash light does not come on, you have either a blown fuse or a 4th gear switch that is not working.

Put the cover back on the relay, plug it back in and with the engine OFF, ignition ON, shifter in 4th, try to engage the OD. If the dash light comes on, does the solenoid by the OD unit click at the same time? If it clicks and still no OD, you need new actuating piston seals to get your OD working again.

If the dash light does not come on, pull the shift lever further to the rear and right and holding it there try the button again. If the dash light comes on then goes out when you move the shift lever, the 4th gear switch is bad.

Duane

Duane,

Well, I checked as you described. I can't get the dash light to come on when in 4th gear. There is 12V at the OD switch on the shifter and continunity between each switch leads and the relay socket. The fuse is OK as well. No click is made by the relay. This would suggest that the 4th gear switch or wires leading are bad, right? Where is the 4th gear switch located? Can I bypass it to see if I can get the light on the dash to turn on?

Thanks,
Steve
--
1986 745 w/ M46 200K since new, 1995 965 104K

If you pull the relay out of the socket, there should be continuity between the red wire lead and any ground when in 4th gear. Also between the black wire and ground.

If not, the switch is on the top right side of the OD. There is a single red wire leading to it. Access is a pain but doable.

If you ground that wire, the relay should function and the dash light react with the switch. If you leave it grounded, you will not disengage the OD when shifting out of 4th. This could lead to a damaging situatiuon where the OD is still energized and you drive in reverse. If the conditions are right, you will damage your OD to the point of very much $$$ to repair.

Duane

Thanks, Duane. I'll check it out.

Perhaps you could help me with my other M46 in my 1986 740 as well. The dash light comes on and the overdrive engages, but only stays in gear when above 65mph. Otherwise it slipps in and out of OD. I had this problem about 7 years ago and changing the fluid made it go away. I recently changed the fluid (and cleaned the filter above the pan) but it still comes out of OD. When this happens, the dash light is still on.

Thank you!
-Steve

This one needs new actuating piston seals.

See the "Features" at the top of the Brickboard page, click on 700-900 FAQ, scroll down to M46 rebuild(?)and read what has to be done.

Duane

Bummer for me.

But thanks, Duane. Having read your contribution to the FAQ, you certainly are the ODGuru!

I think that I may live with the condition of my OD for the time being.

-Steve
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1986 745 w/ M46 200K since new, 1995 965 104K

Thanks, Duane!

The light does not come on when I push the button in 4th gear. I'll try moving the shifter around and check the fuses and let you know.

-Steve
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1986 745 w/ M46 200K since new, 1995 965 104K