1973 280SEL 4.5 instrument lights

[fourbuds]

My speedo and instrument lights (fuel,oil press,etc) do not operate, but everything else works fine. All the fuses look good. I acquired the car 3 months ago so I don't know if this is a recent problem since I had not driven it at night until last week. Any ideas?

[Tomguy]

Have you tried slowly turning the dimmer back-and-forth? This is usually there the problem lies - the coiled-wire resistor inside corrodes on the surface and causes poor contact. You can EASILY pull the cluster (if the knurled nut has already been removed) and take this out to clean it off gently with a piece of fine steel wool.

[j9fd3s]

ive fixed the last 2 by just turning the knob back and forth a few times. you can take it apart and clean it too, pretty easy

[deafen]

I'm getting ready to dig into this. I tried rotating the dimmer, no dice.

Because my hands and arms are way too big to get to the knurled nut (and trust me, I've tried), I'm going to toss a $20 at an independent to get it off for me. So two questions:

1. To get to the dimmer rheostat, is it necessary to pull the speedo cable?

2. I can't find a replacement rheostat in the aftermarket. I assume the OE part runs $30-40. Should I just bypass it and leave them on full bright?

Thanks!

Hal

[nhdoc]

Don't give up so easily...I had a 1982 240D which I had to turn the rheostat back and forth about 300 times before it started working, eventually it flashed a couple of times and then worked reliably after that. Sometimes they get so oxidized you just have to work on them but I would bet that with some patience you can get it working for no $$$ at all.

[deafen]

Holy crap, you were right! I was being too impatient. It took about five more minutes of continuous twisting, but sure enough, a couple flickers, then it started working!

And right after I finished, the knob broke off.

Turns out it was broken before and had been superglued in place, and all my messing busted the bad joint. I'm going to clean the old cyanoacrylate residue off, then glue it back together with model airplane glue to get a real weld.

Thanks for the encouragement! It worked!

[nhdoc]

Originally Posted by deafen

Holy crap, you were right! I was being too impatient. It took about five more minutes of continuous twisting, but sure enough, a couple flickers, then it started working!

And right after I finished, the knob broke off.

Turns out it was broken before and had been superglued in place, and all my messing busted the bad joint. I'm going to clean the old cyanoacrylate residue off, then glue it back together with model airplane glue to get a real weld.

Thanks for the encouragement! It worked!

That's what this board is all about...glad I could be of some assistance!

Good luck with the glue project.

I would bet 95% of the rheostats replaced could be made to work again by just excersizing them this way. Using de-ox-it on it would probably fix the other 5%