I am still working on the electric seat controls for my 1982 300SD. Upon getting a good connection, the power leads, both the red and the red/white had voltage. I have continuity on every wire from the switch to the seat connector. Before installing the seat, I tested every fuction by applying 12V to each wire pair, and the reversing polarity to verify reverse function.
Sill, I have no function from the rear half of the switch--the rear rise and fall and the recline.
What have I missed?

Have you taken the switch apart and cleaned it??

Theres a good post on here from donbryce that details it.

Did it to both of mine and they work perfectly.

__________________
1988 W126 420 SE

beware of fundamentalists!

Yes, I have cleaned the switch. I have even purchased an extra switch from a junker, and cleaned it--just incase there was a break in the circut--with no change in function. I am getting better at disassembly and reassembly of those switches than anyone should be.

since you have power and assuming your motor is ok, it could be the black covered plastic hex cable(from seat motor to gear) has stripped and is turning freely. try pushing on the cable as you activate the switch to see if it will catch.

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1993 Mercedes Benz 300D 2.5 205K (ex wife's)
1984 Mercedes Benz 300SD 320K (SOLD)
2004 Mercedes Benz C240 75K
1995 GMC Sierra 2WD 5.7L 188K
1983 Mercedes Benz 300SD 239K (SOLD)
1987 BMW 325i 220K (SOLD FOR SALVAGE)

609 Certification

Thanks for the idea, but there is simply no motor function. I may wire a secondary switch just to prove to myself, again, that the seat is OK.

Did the motor run out of the car? I'm just not sure from your OP?

Ifit did and doesn't when you put it back into the car there has got to be a break in continuity somewhere (stating the obvious - I know).

Rear height and recline are 2 different motors - it would be odd, but not impossible that 2 motors are blown.

__________________
1988 W126 420 SE

beware of fundamentalists!