W124 Electrical Help please...

[MrBluebell]

Hey everybody.

I'm new to the Mercedes forums as i have just purchased a 1988 W124 260E auto with 81K on the clock.

So far I'm loving the car, the body is rock solid and the engine is lively for its 29 years.

Where I'm not so happy is on the inside as my rear electric windows don't work. I initially hoped this was a fuse issue but having found the fuses work corner to corner this is not the case. I have not had chance to strip the rear doors and check motors etc so just wondered if there was any common causes for this?

Also, my dash, window switches and heater controls do not light up with the headlights. Warning lights and all other interior illumination works. I have looked around on google and heard about he convenience control box under rear seat but i don't seem to have one. I have also heard about the potentiometer failing in the back of the cluster.

Anybody have anymore time saving info on either issue?

Thanks for any replies in advance.

[Stegel]

MrBluebell said:

Hey everybody.

I'm new to the Mercedes forums as i have just purchased a 1988 W124 260E auto with 81K on the clock.

So far I'm loving the car, the body is rock solid and the engine is lively for its 29 years.

Where I'm not so happy is on the inside as my rear electric windows don't work. I initially hoped this was a fuse issue but having found the fuses work corner to corner this is not the case. I have not had chance to strip the rear doors and check motors etc so just wondered if there was any common causes for this?

Also, my dash, window switches and heater controls do not light up with the headlights. Warning lights and all other interior illumination works. I have looked around on google and heard about he convenience control box under rear seat but i don't seem to have one. I have also heard about the potentiometer failing in the back of the cluster.

Anybody have anymore time saving info on either issue?

Thanks for any replies in advance.

Could the window issue be the child isolation switch playing up (I presume your car has one - my '95 car does?). May be worth checking and cleaning it.
On the dash lights, my car's lights only worked for about 20% of the range of the potentiometer. I stripped it down and a great deal of flaking muck came out. It still does not work on maximum brightness, but that's too bright anyway, and now works fine for the rest of the range. I did have to change about half the dash lamps, so it could simply be the bulbs have gone!

[MrBluebell]

Thank you for the reply.

I may look at the safety switch, it would make sense if this has failed to lose both windows.

On the dash lights, does the potentiometer control the heater illumination etc as well as the binnacle?

[Stegel]

From memory, yes it dims the heater switches. Every bulb had failed in my car when I bought it.