After an unfortunate encounter with water that left the floor soaked I have some electrical gremlins to sort out.

Part# 124 800 1578 is under the driver's side rear seat, and it buzzes like crazy when I put the key in, eventually slowing down and stopping. The vacuum supply pump also stopped working. Alarm non-functioning as well, though it worked great while I was driving home in a storm at 3am!

I can find very little information on this part, what it does and what it's connected to. Can anybody else shed some light on this?

I unplugged the power to get it to quit, I'll take it for a drive soon and hope it doesn't affect anything important. I'm guessing it is only part of the door locks.

Thanks!

__________________

Head restraint release actuator?? About the only vacuum solenoid that should be back there is for the head restraints.

Try plugging part number into EPC.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Pulled up part number on EPC, confirmed this is the rear headreast adjustment feature valve.

Takes engine vacuum (thru the white hose) to the pods beneath the headrests.

The valve has switched 12 V dc on it (from fuse 1) and accepts a control pulse from the dash switch. If you have a rear sunshade there is an interlock in the control line from the switch, to prevent lowering the headrest unless the sunshade is completely retracted.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks Jay!!

__________________

Suggest removing the valve (plug the vacuum line from the engine) and baking it in a warm oven or over a heat vent for a few days. If that doesn't help you'll probably have to replace it or do without. Personally I like having the rear headrests down out of the way (if no rear passengers) for better visibility.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Good suggestion, I'll post back results.

__________________