Oldsmobilliam

My lights behind the speedo arent working. We replaced the bulbs to no avail. I am thinking it may be the dimmer control on the light switch. The headlights work fine but not the dash lights. Any suggestions would be delightful.

Olds64

When you replaced the bulbs did you check for 12V coming to the light? If it isn't there then trace it back to the dimmer switch and make sure 12V is going to the dimmer switch. If the dimmer switch doesn't have 12V then you have to figure out why. The easiest thing to start with would be to check all of your fuses.

Lady72nRob71

On some models, the INST LMPS fuse is the one you are seeking.
If the fuses are good, the dimmer switch on the light switch may be bad. Rotating it quickly back and forth may cause them to flicker. If so, replace the switch.

Oldsmobilliam

I remember it did used to flicker, and for a while there it would come back on with a few moderate slaps to the dash with my hands.

I will try those ideas, sirs.

joe_padavano

I have had the rheostat contact in the light switch go bad, so that is a possibility.

Yellowstatue

A few moderate slaps with a big hammer would probably work better X2 on changing the switch...my '57 dash lights didn't work either and it was a bad connection at the rivet holding the contacts together inside the switch...

rocketraider

If the INST LPS fuse tests good, check the ground straps behind the dash. There's one that circles the headlight switch and another that surrounds the instrument cluster and radio-HVAC controls area.

Does the dimmer rheostat operate smoothly thru its travel or are there rough spots in it?

Olds64

I wonder, is this rheostat easy to purchase, or is it a part made of unobtanium?

rocketraider

It's part of the headlight switch.

For some reason I thought you were talking about a 70-72 A-body car. I see you have an early 80s Ninety Eight. The dash cluster lights seem to be a recurring problem on 77-84 B/C cars; on my CC wagon the right side speedo lighting stays off over half the time but on occasion will light up normally, and sometimes the left side lighting will blink off. I think it's probably a squirrelly connection on the printed circuit behind the cluster. What's really aggravating is the carrier has to come out of the dash to inspect the PC.

By the time you've pulled the speedometer head to access the lamps, it doesn't take much more to remove the carrier.

Oldsmobilliam

it spins just fine, when i turn it all the way the overhead light comes on.

Dan Wirth

I agree with Olds64. This should be done first, then isolate trouble further to the switch, if necessary.

Lovin87olds

I have the same problem with my 87 Salon. Although i have not checked the volts coming from the lamp sockets, I did change the bulbs and checked the fuses (fuse's are good). I am going to order the dimmer switch today since im at work lol I did find out that there was a engine compartment fire in the car, funny thing is, is that there are no signs of a fire in it. Maybe the previous owner cleaned it up but nothing i could see gave me a clue that there was, hope none of the wires are melted or burned, I'm not big on electrical stuff.