1972 280SE W108 Dashboard Lights Don't Work

[Baxterdown]

The dashboard lights (instrument cluster, heater, and radio) in my 1972 280SE don't work. Initially I thought the light bulbs in the instrument cluster were burnt, but then I found the heater and radio both light up. So, I started to doubt it's the cluster bulbs.

I checked the #7 fuse to make sure it wasn't burned. And it's not. Also, the tail lights (which are controlled by that fuse) work fine.

Any thoughts on what could be before I attempt to remove the instrument cluster?

Thanks!

Jose

[ScooterABC]

The dash potentiometer in the cluster.... try wiggling it around a bit.

[124Coupe]

Originally Posted by ScooterABC

The dash potentiometer in the cluster.... try wiggling it around a bit.

+1 My same thought.

[Baxterdown]

Thanks guys.

Is the potentiometer the knob on the cluster? And by wiggling it do you mean turning it?

Here's where I'm at with that:

The knob on the left, which from what I have read adjusts the lights, turns and turns and turns and turns and nothing. It appears to be spring loaded as I can pull it out and snaps back in. But no lights come on or fade in.

The knob on the right, which from what I have read adjusts the trip odometer is stuck and won't move. It appears to be pulled out. I've tried turning it but nothing. I haven't tried turning it hard as I don't want to brake it.

I don't have an owners manual, so a lot of this stuff is hard for me to guess what it does and how to adjust stuff. If you guys can provide me a bit more information on what you mean by wiggling and what exactly is the dash potentiometer, I'm happy to give it a try.

Thanks!

Jose

[Idle]

You have to remove the instrument pod to get to the adjustment for the instrument lights.

Once you do you will find on the back side of the instrument panel a white ceramic thing that will line up with the instrument light adjustment dial. This has failed. It is a very common thing that can either be fixed easily or not at all.

I usually spray the insides of the thing with some contact cleaner from Radio Shack and turn the knob back and forth a few times to clean up the contacts. If that does not work then all I know to do is replace it.

They are quite expensive for what you get; around $100 or so. But there are always a few for sale on Ebay or you can post an ad in the 'wanted' section of this forum.

Of course if you buy a new one you will be fixed up for the next 30 years.

Pulling the instrument cluster is easy after you have done it a time or two. Look around on-line for instructions on how to do this as it is different from pulling the instruments on any other car.

[Baxterdown]

I found two sets of instructions for removing the instrument cluster in a W108. One here and the other one here.

They both have very similar instructions with the difference that one says to remove the parking brake lever before reaching in the back to remove the plastic screw.

I didn't remove the brake lever but did try reaching under the dash (after removing the cardboard panels) and it's impossible for me to get back there. With that said, the other set of instructions mentioned that in many cases people have already removed the screw and that they rarely put it back on.

My car's instrument cluster moves in and out about two inches. Look at the video I took:

Moving instrument cluster - YouTube

Judging by how much I can move the cluster, do you think the plastic screw in my car has already been removed?

As the video shows, I cannot pull my cluster out any further than a couple of inches. When I try, I tightens up really bad. I'm afraid to break something.

Thanks for all your help!

[280SE Guy]

Did you unscrew the speedometer cable?

[Idle]

If you can remove it any at all the plastic screw is gone. Sometimes the metal bracket the screw is connected to is gone as well. If you were barreling down the road in some third world country you might need the screws to hold the instruments in but on smooth roads the rubber ribbed gasket is really all you need.

Pull the pod out far enough to reach the speedo cable and unscrew it. It turns counter-clockwise. Just let it drop back as it will not fall away too far. There will then be an electrical plug or two which may or may not be difficult to pull off and then there is the oil pressure line that is screwed into the back of the oil pressure gauge that will need to be unscrewed. Watch out here as there is normally some very slight loss of oil. Put a rag or paper towel under the pod to catch the few drops of oil that will come out.

You should then be able to pull the pod out to where you can reach the light adjuster. You will not be able to pull the pod all the way out since the temp gauge might be connected to the temp sensor via a thermocouple (some are and some are not. It s a silver threaded looking line if your car has one.)

The adjuster is normally held in by a screw or two which are easily removed. If there are wires to it they will come off as well. Then it just pulls right out of the back.

[Baxterdown]

Hey guys, thanks for the replies!

280SE Guy, I have not unscrewed the speedometer cable. Actually, I haven't unscrewed anything. The car came "equipped" with the sliding cluster LOL!

Idle, thanks SO MUCH for all of your detailed instructions. I'm gonna leave tackling this project for weekend after next when I have a good eight hours to dedicate to it. Thanks again!

[280SE Guy]

A good idea is to have your cell phone at close reach if you stick your hand up under the dash and it gets stuck

Good luck. Do as much as you can while it is out like replacing all of the light bulbs, if you are capable of removing the entire cluster after removing the speedometer cable, oil sender fitting, temperature sender. and boden cable for the shift indicator you can then take the cluster to your workbench and do some more detailing of it. The insude of the glass tends to get a little crudey on the inside over time, a perfect time to clean it up as it make a big difference.

Regards,

280SE Guy

[Idle]

Wow. I forgot about the shifter cable, but then all my 108's have been floor shifts.

Instructions are bound to be on-line for how to remove the glass for the instruments. It has been awhile since I have done this but it is a wise thing to do as long as it is out.

Some of the early cars had crystal for the glass so it is as pure as it can get. The only way to tell the difference from glass is by weight since they don't really ring when you thump them.

But the glass is also very pure. Be careful with these pieces of glass. Replacements are expensive.

once you get the cluster out you will find it very easy to understand how it all works.

[Clarion]

Does this method work on a 280C? My dash lites, dimmer thingie and Trans lite don't work. Right Turn signal works occasionally. Flasher works...?

[Baxterdown]

Idle,

I found the attached photo below of the back of a W108 instrument cluster. This helps me a lot as now I know what the back looks like.

Judging by what I see in the photo and how I can jiggle my car's cluster side to side but not take it out, I'm wondering if that center screw in my car is still bolted... If it were not, wouldn't I be able to slide the cluster all the way out easily?

[124Coupe]

Originally Posted by Baxterdown

If it were not, wouldn't I be able to slide the cluster all the way out easily?

I've worked on my 4.5's cluster with it still in mostly place however the speedometer cable has to be unscrewed to gain access. Make sure to place a towel over the steering column to prevent scratches and as 280SE guy said, it's a good time to replace all the bulbs and clean.

[Baxterdown]

Apologies if I'm not making myself clear. Look at this video:

Moving instrument cluster - YouTube

I can slide the cluster out about two inches. That's it. My question is past that do I have to pull HARD to slide it out completely OR should it slide out easily?

Thanks!