W124 Very dim cluster problem - PeachParts Mercedes-Benz Forum

ps2cho · #1 08-17-2010, 03:52 AM

Trying to get my interior issues all sorted out...

Problem is my cluster is VERY dimly lit. Not the best photo, but you get the idea...The bottom half has little to no illumination at all.
Pic shown after the cluster swap hence the wrong odometer...

1) I have replaced all bulbs
2) I have switched clusters
3) Replaced rheostat and turned it. None make much difference.
-- The top half is lit about twice as much as the bottom is. I can barely see the bottom half at night...

Any ideas what could be the issue? All the cluster items function perfectly...It is just the lighting.

Spetz · #2 08-17-2010, 04:33 AM

You probably know this, but the button that zeros the odometer also controls the brightness of the interior lights when turned.

babymog · #3 08-17-2010, 09:44 AM

What about the rest of the dash and console lights, normal or also very dim? They dim together with the rheostat in the cluster.

latief · #4 08-17-2010, 10:28 AM

melted prisms inside cluster (s)? there is an updated design in the 1990s.....

tbomachines · #5 08-17-2010, 11:50 AM

Quote:

Originally Posted by latief

melted prisms inside cluster (s)? there is an updated design in the 1990s.....

X2, or in the case of my w126 they had dust crusted on them, which was then seared by the heat of the bulbs and made for a nice black coating on the prisms.

280EZRider · #6 08-17-2010, 12:12 PM

Assuming the complete line of components is dim, the very first thing I would do for trouble-shooting is completely bypass the rheostat and see what kind of lighting you get. The problem could be the with the circuit board just beyond the rheostat.

ps2cho · #7 08-17-2010, 12:39 PM

Quote:

Originally Posted by 280EZRider

Assuming the complete line of components is dim, the very first thing I would do for trouble-shooting is completely bypass the rheostat and see what kind of lighting you get. The problem could be the with the circuit board just beyond the rheostat.

The dummy lights are OK....It is just the illumination ones.
How do I bypass the rheostat? Yes I have turned it of course...Like I said, it makes little to no difference.

Since I already swapped the cluster, I thought maybe it was some electrical issue maybe.

I checked the prisms and they were not melted or dusty. I cleaned them all up.

babymog · #8 08-17-2010, 12:49 PM

As I mentioned, all switches in the dash and console dim with the same rheostat.

ARE ALL SWITCHES DIM OR ONLY THE CLUSTER?

You might get the answer even without this critical piece of information, but you might also get a lot of wrong answers.

ps2cho · #9 08-17-2010, 12:51 PM

Quote:

Originally Posted by babymog

As I mentioned, all switches in the dash and console dim with the same rheostat.

ARE ALL SWITCHES DIM OR ONLY THE CLUSTER?

You might get the answer even without this critical piece of information, but you might also get a lot of wrong answers.

Only the cluster. My center shifter console bulbs are super bright. I never knew the rheostat controlled those too?

...maybe I've just never paid attention to it.

I'll go see if the rheostat dims the console or not right now...

ps2cho · #10 08-17-2010, 01:03 PM

Thanks this may really route down the issue...

When I turn the rheostat, the center console lights go out completely, then if I turn a little more or wiggle the knob, they flicker and come back on. They definitely dim as I turn the rheostat, but since the bulb flickers and goes on and off....Maybe it is that electrical board?

Come to think of it, that is the only thing I haven't replaced so far. Only due to the fact that one is soldered to the clock side. I guess I could unsolder it, swap in a good one and try that?

Sound reasonable?

babymog · #11 08-17-2010, 02:57 PM

That should rule out the rheostat, IIRC there is a ground connection between the boards that is mechanical, not sure that will affect both though.

ps2cho · #12 08-20-2010, 02:13 PM

Got her on the table for surgery.

Anything jump out at you guys?

I see a little 'tarnish?' on some of the metal where the rheostat resides (it is removed obviously)....and also the strip that connects the 2 outer sections together is bent. Not sure if that would cause any issues though?

tbomachines · #13 08-20-2010, 02:30 PM

How about the black plastic casing and prisms? I don't see anything that would jump out from those shots.

ps2cho · #14 08-20-2010, 03:26 PM

As I said earlier, I already in the past swapped the plastic cluster cover (junkyard grab)...but I guess there is the off chance I got one with the same issue. I will plug everything in tonight without the cluster and see what the brightness is like. If everything is bright (especially top vs bottom bulbs), then I guess I can conclude the cluster is bad. If not it's gotta be electrical.

Sorry I like thinking out loud. Especially since I am no electrician, you can get my thought process.

86 300E · #15 08-21-2010, 05:08 AM

similar problem with the dim lights but not only is my cluster dim the other lights are dim and or out.

can you give me some suggestions?