Eloutfi

So I was just about to take out my 1989 Porsche 928S4 out until noticed something weird. When I have the lights down the digital instrument gauge lights are on. When have the head light switch in the second or third position the lights turn off. The lights all in the center console all stop working after this happened like the clock light stopped working, climate control, trip reset light all stopped illuminating when the lights are off or on. Can't see the gauges when driving and I don't know what the issue is. I tried the dimmer under the pod and checked the fuses and still nothing. If anybody has had this problem and knows how fix it let me know as quick as possible.

worf928

Does everything return to normal after you turn the headlights off?

What about if you turn off the engine and then restart?

Does it happen with the engine off, key in 'run' position?

What about the HVAC blower? Does it also 'die' when the lights are turned on?

Eloutfi

Everything in the car works fine and it doesn't die. The A/C, radio, clock, headlights. It just when you turn on the car and the headlight switch is in the first position the digital instrument cluster lights are on and then when you put the headlight switch is in the second or third position all the lights on the digital instrument cluster turn off. The clock and climate control stopped illuminating as well when you put the headlight switch in any position.

ddire333

think you have few possibilities, but by far most likely is the headlight switch is self.

SeanR

How did things react when you adjusted the light dimmer/rheostat?

Petza914

You can take the two wires off the rheostat dimmer and connect them together to test whether it's the rheostat or not. They should be full bright if you do this. If they work with the rheostat jumpered, it's the rheostat - if they don't, it's something else.

Kevin in Atlanta

So, all lights go out with the headlight switch in first or second position.

Digidash model years are different. Pod lights have two paths for headlights on and off.

If pod and clock lights are off with the headlight on then this suggests the issue precedes where the pod illumination forks off.

Not having the wiring diagram handy I would guess the issue is the headlight switch itself. Find another one and test it.

dr bob

Have you done any work in that area recently?


I would start with the very basic stuff. Clean The Grounds as the very first step. Next, disconnect, remove, and clean the rheostat for the dash lights. Use DeOxit or your favorite contact cleaner spray to remove the last bits of corrosion from the wire windings, maybe with a little agitation with a toothbrush.

The digi-dash cluster lights are a little interesting, in that they are brighter with the headlights off for daytime illumination, dim down some for night time use. Chase circuits current flow and wiring only after you've gone after the basics. Pulling and pushing on wires is as likely to cause damage as to solve anything, for the most part. The exception is the edge connectors at the bottom of the cluster, which can be slid off and right back on to the card-edge connectors on the cluster back-plane. These are functionally "self-wiping" connections, so the simple act of sliding them off and right back on will scrub light oxidation from the contact surfaces.

Eloutfi

Thank you guys for all the suggestions.The lights for the gauges on the digi dash all turn off when the headlight switch is in the second or third position, but when the switch is in the first position the gauges on the digi dash all turn on. The clock and climate control stopped illuminating for some reason when this started happening. The car had not trouble on Thursday. The gauge lights as well as the clock light, climate control light all work fine until yesterday night. I tried cleaning the headlight fuse. The headlight switch I think might be the culprit. I also tried the instrument cluster dimmer and it did nothing.

Eloutfi

So I think I just fixed the problem. Thank you dr. bob and Petza 914 for suggesting to clean the rheostat. I just unscrewed the bolt and clean the connection and now everything is back to normal. Thank you all for the help.

Thank you
Eli Loutfi

Eloutfi

So after a few days now, I'm glad to say that the rheostat was the issue. I used a spare one i had, but I order a new one from Porsche and installed it and everything is back to normal. The instrument cluster lights work turn on when the headlight switch is in the second or third position, clock now, trip reset and climate control illuminate. Thank you all for the help.

Thank you
Eli Loutfi