1985 300D is having some crazy electrical issue, all windows, turnsignals, fuel gauge and tach all suddenly stopped working. Every once in a while everything will start working for a minute and go out again. Now it hardly ever works.

Things I have done:
-Changed all fuses
-Replaced electrical portion of ignition switch
-Changed window switches
-Removed front door panels and made sure no juice getting to window motors

I have found I get no juice to window motors, @ fuse box I am getting no juice to either window fuse. I can jump from a fuse with juice to the window fuses and all windows work perfect. The hazard lights work, the running lights work but no turnsignals. When I hooked up the new electrical part at the ignition everything worked perfect for about 5 tries then it went out again(I thought I had it). What else could I be looking at as being the culprit. You think I could have a problem with the part of the wiring harness that plugs into the ignition switch? Any help is appreciated.

Perhaps a bad ground? Pull the cluster and check the ground points back there. A LOT of stuff grounds there and if something is wrong there (loose, corroded, etc.) , I would imagine a lot of crazy, seemingly unrelated stuff would stop working.

KenB

With so much going out at once I would check the main earth strap.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Any question that contains the words "Crazy Electrical Problem" I would answer with a statement that included "checking grounds" (or in aussie land Earth).

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

As mentioned, check the ground strap from the engine to the body. It is on the drivers side below the oil filter housing. remove it and check to see there is no rust or other contaminates in the contact area and make sure it is tight.

behind the cluster is another grounding place, the brown wires are the ground wires.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

The windows get their power through a relay that operates on a different fuse, #12 in the 1985 300D. If the relay doesn't get power or if it is fried, none of the windows will work. The relay normally comes on with the ignition switch. I don't remember where that relay lives in your car.

Fuse #12 also powers the brake and turn lamps, the cruise control, the tachometer, and the instrument cluster. Since you have changed the fuses, the next thing to look for is a corroded contact, partially broken wire, or as the other posters have reminded us, a bad ground, especially W1, behind the instrument cluster.

__________________

"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

Examine your ground cables and your battery cables carefully, don't just look touch/jiggle them to make sure they are fully intact. Make sure you have lots of light to work with. If necessary, use an inspection mirror inside the dash.

I had a similar problem with a Volvo 700 series and it was a major ground strap that had somehow cracked or been slit almost all the way through. It would be fine for days or weeks then one major road bump and I would lose electricals.

Huge fun at -20C in the Canadian winter....

Good luck with it.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22