Dash lights flicker when headlights are on - PeachParts Mercedes-Benz Forum

byronnash · #1 02-18-2010, 12:16 PM

When I turn my headlights on, the entire dash goes nuts. All the lights start flashing and sometimes the gauges peg or go off. It also seems like they flicker in relation to the wheel RPM. When I sit still, some lights may be on, but don't flicker, but as I accelerate, the flickering increases. There is definitely something screwing going on in the cluster I guess.

I'm new to these cars, is this a difficult thing to troubleshoot?

okyoureabeast · #2 02-18-2010, 12:47 PM

Whoa sounds like a really bad ground. Check to see if the negative (ground) side of the battery is tight. Also consider pulling the cluster out and running an extra ground wire to the chassis.

Codifex Maximus · #3 02-18-2010, 12:50 PM

Quote:

Originally Posted by byronnash

When I turn my headlights on, the entire dash goes nuts. All the lights start flashing and sometimes the gauges peg or go off. It also seems like they flicker in relation to the wheel RPM. When I sit still, some lights may be on, but don't flicker, but as I accelerate, the flickering increases. There is definitely something screwing going on in the cluster I guess.

I'm new to these cars, is this a difficult thing to troubleshoot?

Probably the Instrument Light Rheostat. You could clean or bypass the one you have or replace it. The rheostat should be on the instrument cluster on the left hand side on the bottom - it is also the trip odometer reset.

For the replacement option, go to the top of this page and look for the Buy Parts button to order a new one.

For the repair/bypass, solder a wire across the two visible studs on the back of the rheostat.

Hmm... ground. Good call okyourabeast.

byronnash · #4 02-18-2010, 02:49 PM

Where do you connect the ground wire to on the cluster?

rrgrassi · #5 02-18-2010, 03:58 PM

Anywhere on the bare metal or under one of the screwes that contacts the bare metal on the cluster.

byronnash · #6 03-05-2010, 04:04 PM

I'm planning on pulling the cluster tomorrow to fix the ground problem. I am also going to go ahead and solder the rheostat since it seems to be a common problem. Is there anything else I should look for or take care of while I have it out? My tach isn't working right now but I don't know the cause yet. I don't want to pull the cluster in and out if I don't have to, so it would be nice to take care of a few things at once.

PaJon · #7 03-05-2010, 07:25 PM

Quote:

Originally Posted by byronnash

Is there anything else I should look for or take care of while I have it out?

Might want to change the bulbs with it out.

byronnash · #8 03-06-2010, 09:19 PM

I think my small repair is a success. I ran a small wire from a screw on the back of the cluster to a spot on the chassis right behind the cluster. I didn't disconnect all the wires so it was a little tight getting the screw in on the chassis. Someone already soldered the rheostat. I drove it briefly tonight and I'm not getting any flicker or weird stuff when the headlights are on.