Power Windows Dead. Where is G102 ground on 450SL?
 

In my 1980 450SL, I've been putting up with a flaky cruise control for a while, and low speed on my wipers that only works when I hit a good bump, but now that both power windows quit on me, it's time to track this gremlin down. I think my problem is a bad G102 ground, because according to my factory wiring diagram, all my bad bits terminate there. Trouble is, I can't find the darn thing.

My wiring diagram says (under Component Locations) that it will be "behind instrument cluster". I pulled my steering wheel, pulled out the cluster and --- nothing. Then I saw Gilly mentioned in thread 17926 that on somebody's 500SL they'd find it to the right of the glove box after pulling the box. I pulled the glove box and -- nothing. I give up. Where is this beastie? It looks like 8 or 9 different items terminate there, so I think I'm looking for a big screw with a bunch of brown wires going to it, but so far no dice. To the right of my glove box -- waaaaay off to the right, I see a bundle of brown wires disappear into the body work. Can someone help me with a few landmarks and what it will look like when I get there? Thanks for any assistance.

G102 ground on ALL 450SL's is bolted to the "TOP" of the steering column behind the instrument cluster. There should be about 12 BROWN wires there!

Thanks, M.B. Doc. With your guidance, I'll take the cluster (back) out and hunt some more for that ground so I can fix my flaky wipers and cruise control.

But an update on the dead power windows is in order for folks who find this thread with a "search". I had previously narrowed my suspects to the G102 ground or the Power Window relay. Having given up on finding G102, I went looking for the relay, which my 107 Service Manual said (mistakenly, it turns out) was under the Left Hand Kick Panel.

Because of the manual, I ignored the two shiny metal relays under the Right Hand Kick Panel (over the fuse box), saying to myself, "no, that couldn't be it because there are two matching relays, not one, and its on the wrong side". So today I stopped at All Mercedes, picked up a new "Window Regulator Relay(?)" -- noted it was a black plastic relay with flat stake terminals not round pins like the metal ones had, and with renewed confidence, tore the left hand side of my car apart looking for anything like that new plastic relay. Nothing. There's no wiring under that panel at all. Finally, before I buttoned things up for the night, I said, "The heck with it... I'm going to swap those two identical shiny metal relays over on the right side over the fuse box even though they're on the wrong side according to the book and don't look anything like the $26 widget I just bought".

Presto. Working windows. One of those two relays must be the window relay (heaven knows what the other one is). So tommorow I'll go trade the wrong part I bought for the right part I need and away I'll go with operable windows.

I did manage to follow those brown wires to the right of my glove box I mentioned in my last post and sure enough, by removing the underdash panel on the right side, I found that like 10 of them all went to two big grounding screws screwed into the bulkhead. Nice and clean and tight, so that wasn't my flaky ground. I thought sure I'd found the elusive G102 there until I saw MB Doc's authoritative reply.