ignition buzzer and dome light relay location - PeachParts Mercedes-Benz Forum

Boston Benz · #1 01-28-2009, 09:50 PM

RE: my 1995 E320 I have read numerous posts (via the search function) about this relay's location. Many posts say the buzzer relay is behind the instrument cluster, I also noticed that all those people who responded with that answer own diesels. On a gas model, is this dome light/buzzer relay near the brake pedal? I can't find it. I removed the black plastic kick panel, should I remove the color-matched knee bolster under the steering wheel too? Is it way up above the brake pedal?

I read a few receipts from the p.o. where a mechanic attempted to "get rid of" the buzzing sound. Obviously, the driver's door dome light control doesn't work. I need to find this relay to see if it's attached/detached.

Jeremy5848 · #2 01-29-2009, 12:47 AM

I just took the warning relay (buzzer built in) off a 1992 300E 4-Matic. It was definitely located behind the instrument cluster, on a bracket that also holds a relay for the lighted switches in the console. (This latter relay allows the dimmer rheostat to handle all of the lights without overloading.)

In the attached photo, the dash light relay and the warning relay are shown side by side in my 1987 300D Turbo (sorry to pollute your forum with my diesel

). AFAIK, all 124s are built this way. The thing on top with the green wires is a distribution block for the engine speed (tachometer) signal. It is used for various things that need to know RPMs, like EGR and such.

To remove the bracket holding the two relays, you need to remove the bolt shown with the arrow as well as another bolt, hard to see, all the way back at the firewall. An 8mm or 10mm socket (sorry, forget which) on a long extension works. Put something sticky on the socket so you won't drop the rear screw into the depths – I did.

Once the two screws are out, you can move the bracket enough to unplug the cables from the two relays and then disconnect the green wire distributor and pull the bracket with the relays out. Once out, you can individually remove the relays from the bracket. They are held on with one screw each but buried at the back of the cluster opening where you can't get at them. It's a real PITA, unfortunately.

If all you want to do is to test the relay by substituting a known good one (mine was bad when I got my '87) you may be able to unplug the warning relay's cable without unscrewing the bracket (it's the one on the LEFT according to the factory electrical manual). Mercedes refers to it as "Warning Module N2/4 – seat belt, keys, lamps." Plug the cable into the new relay and see if it works.

BTW, if your warning relay is bad, I have one for sale ($10, free shipping in USA). See my post in the "Parts for Sale" section. Part #004 545 07 32.

Jeremy

Boston Benz · #3 01-29-2009, 09:17 AM

Right, I remember reading your post in the search I did. OK, I'll try going behind the cluster. It's just that other people have said it's above the brake pedal, well below the cluster...

Boston Benz · #4 01-29-2009, 09:19 AM

Also, my guess is that it's unplugged (this relay) more than it's defective since the receipts from the p.o. indicated that he didn't like the noise and since the dome light doesn't work with the driver's door open...

Jeremy5848 · #5 01-29-2009, 12:09 PM

A good guess. The "trigger" input (that's what Mercedes calls it) for the dome light indeed comes from the warning relay. An unplugged relay will cause what you are seeing. Experiment: does the right front door turn on the dome light? Do the puddle lamps work?

Jeremy

Boston Benz · #6 01-29-2009, 02:26 PM

Yes & yes. The other doors activate the dome light(s) and all the puddle lights do work. So, pull out the instrument cluster I imagine?

Jeremy5848 · #7 01-30-2009, 12:56 AM

Yes, you can either buy a factory tool (pair of hooks), an aftermarket version of the same thing, or make a pair from stiff wire (coat hanger wire works fairly well). Insert the hooks at the left and right edges of the cluster where they will catch on serrations built into the plastic casting. You may want to disconnect the battery first; not absolutely necessary but nice if you are pulling the cluster for the very first time.

If the cluster has never been out, it will be a tough pull the first time (the rubber pads tend to stick), just keep at it. You need to release the speedo cable from its hook at the base of the steering column, then pull the cluster out enough to get your hand in and unscrew the cable from the speedometer. Then unplug all of the various cables. I like to start at the right side but do whatever works best for you. The lamps in the right-hand row come out on pigtail leads while the ones on the left side stay with the cluster. Once all the wires are unplugged, the only thing left is to unplug the rubber hose for the "Economy" gauge and the cluster is free. Adjust the steering wheel all the way out to make room and carefully lift the cluster out. With the cluster out, you will be able to see into the hole and determine whether that relay is unplugged.