Removing instrument cluster on W115

[Mike D]

The tape is covering the coils of the light dimming rheostat for some reason. Who knows why? Perhaps someone felt it could cause a short when installed.

The unit separates easily enough. Remove the screws around the perimeter and the unit lifts out. Remove the speedometer side (metal plate) first. Clean the lenses with mild, soapy water or denatured alcohol and a soft cloth. Check the lens for a tight fit. The lenses are secured in the case by means of twisted metal pieces. These are very brittle so don't go "gorilla" on them trying to bend them. A dollop of hot glue on the edges works to secure a loose lens. If you decide to use a clear silicone instead of hot glue then allow the sealer to sit for a couple of days to "gas out" before re-assembly.

When re-installing pay attention to the rheostat shaft's alignment. The adjusting knob stays in the housing and you need to slide the shaft into it.

[R72benz]

I removed the front from my 108 instrument panel and cleaned the glass. Not real tough and made a huge difference in appearance. The taped device appears to be the dash lighting reostat. They are problematic and many wire a jumper on them to operate at full brightness. This may be what happened here. They are still available for purchase if you like dimming the dash lighting.

[j-galap]

Thanks for the advice! Yup, it was very easy in the end - I took it all apart and found some of the plastic tabs around each dial had snapped off (which explained the rattling), so repaired those, replaced the burnt-out LEDs and polished up the glass.

After that, I reinstalled it all and... no dash illumination, argh! Seems something has gone awry.

I did clean up the rheostat too during my tinkering, but seems like something is still amiss with it. I also realized that the reason it was electrical taped up is because someone had already bridged it with some extra wiring. I've not messed around with an instrument cluster before so wasn't aware that the wire was an extra until I took a closer look.

Anyway, a couple of questions as a result.

Is this spring (see image) supposed to just sit in it's trough and only be attached at one end, or should it be fixed to something at each end? Mine is currently attached at the end with the metal fixture. The knob should then run across the spring in it's trough fairly smoothly if it's all operating properly I assume..?



Secondly, I assume that if I bridge these two pin connectors with a wire the dash lights should work at full brightness permanently, correct? I want to get the rheostat working but it's useful for testing of course!



Thanks!

[Mike D]

Yes, those two pins are the contacts. If you don't replace the rheostat assembly the adjuster knob will rattle. Bridge the terminal ends of the coiled spring with a bit of wire for full brightness.