126 "key on" electrical failure-- relay vs keyswitch?? - PeachParts Mercedes-Benz Forum

ajrn · #1 10-04-2007, 08:21 PM

Okay..

Tuesday night, none of my windows worked.. I'd written it off, and just told the state trooper I needed to open the door to hand him my license.. (nope, not joking) For the record, I wasn't ticketed..

I drove home, no issues, the next day the windows were working.. (hmm)

That night it rained, and I noticed my wipers didn't work.. (ugh)

Today, I was going to Autozone to pick up "license plate" bulbs (the reason I was stopped)-- and the windows, and the wipers, AND the instrument cluster were dead..

Autozone is less than a mile from me, so I came there and back.. I pulled one of the relays (the ice cubes?) in the fuse box, to see if they had one-- of course they didn't but I like to frustrate the counter monkeys..

I rotated the relays all one position clockwise (there are 4 of them) then tried it, not getting any result. I rotated them again 1 position clockwise-- again without result, hoping I had one that wasn't working, and would find, at least a "workaround.."

I checked every fuse in the box, with an ohm meter.. Nope, they're all okay..

There were a couple other relays in the box-- is one a "key on" relay?? Or is the problem my key switch itself??

Interestingly-- the blower motor for the heater still works, so does the moonroof?? That was what was making me think "relay" versus key switch..

As always-- any help appreciated..

AJ

ajrn · #2 10-07-2007, 07:15 AM

Hearing nothing here-- I went to the Yahoo Diesel Discussion group.. Replacing ALL the fuses, was suggested.. While I sorta thought, uh huh-- too simple, already checked the fuses, guys-- yesterday, I broke down and took the advice...

Much to my embarassment-- copper fuses were all she needed..

I went to Advance Auto, bought about $7 in (Buss brand) fuses.. Pulled all the blue ones, red ones, and white ones.. I don't get it-- none of the old ones were blown-- I retested them all.. I guess they weren't getting enough amperage thru them to blow them, but they'd just went thru enough hot/cold cycles that they didn't "cut it" any longer..

I've kept the old ones, as "emergent" spares.. I may take the new ones, get ohm readings off them-- and use that as a "benchmark" to decide if the fuses are worth keeping (even as spares)..

I guess it was hard to believe it was fuses-- but I guess like everything else, they're disposable for a reason..

...I think "bulk" replacement in my 81 240D will be next.

AJ

tangofox007 · #3 10-07-2007, 09:31 AM

Anyone with aluminum fuses would do well to replace them with the copper/brass versions. Aluminum will eventually oxidize to the point that it prevents good electrical contact, even thought the fuse itself remains intact.