Toga

Hi gentlemen,

my instruments lighting isn't working anymore

I checked the fuses: all good; I checked the licence plate lighting: working; I checked the bulbs: all ok

did a search here, and it seems I'm the first one to have such a problem



Anyone has an idea?
I leave tomorrow for the European Porsche parade in Vienna and I wonder what's going on.

Thanks for your help

Stealth 993

Did you turn the dimmer all the way up?

CalvinC4S

I think Stealth nailed it, happens.

Toga

yes, I also cheched its connection behind the oil press instrument...

AOW162435

Your wheels took all of the lightness from your instrument bulbs....





Andreas

Warpig

The potentiometer (dimmer dial) for the lights could be defective. I'm pretty sure it is just a standard potentiometer (but have not confirmed this) if it is you can jump it out with a jumper wire to test. IF the control has only two contacts with wires to them it is just set up as a variable resistance that dim the lights and is safe to jump out. IF there are wires going to three separate contacts be careful jumping it out as two of the three wires (usually the outermost connections furthest away from each other) will likely be a direct short if jumped. If you jump it out and the lights are on full blast that's the culprit, if they still are off then keep looking elsewhere. NOTE: be sure the headlight switch is in the position to have the cluster lights on first if it is off they will still be off if you jump out the dimmer control. The next step I would guess is to look at the headlight switch assembly. You could also measure across the dimmer with a volt meter. if there is 12V present the potentiometer is open (bad, unless it uses all three contacts) any voltage below 12 would suggest the potentiometer is working.

Hope I'm not confusing you, I need to work on my technical writing skills.

Nick

Toga

Thanks Warpig I'm going to check this right away.

Andreas thanks for the compliment!

Warpig

Bump. I just want to be sure you see this again as I have edited it while you replied.

Nick

Toga

Well I measured the 3 wires output before jumping them, one is giving 3.92V !?! Surely not enough! Then I measured the potentiometer, and this one seems to work correctly.
The problem is further upstream. Unfortunately, no time to remove and check the headlightswitch now.

Thanks for all Nick.

Toga

Hi all,

after a few researches, I found that there is, in the fuse box, a relay working only for the instruments lighting... I don't know how to check it though. I'll try to swap with one from another 993 while I have the occasion. The local dealer told me he never sold that relay in 10 years and it not even in stock at the importer...

relay is 964 618 103 00. Anyone changed ever that one?

Warpig

I assume this relay lives in the fuse box in the front trunk? If so what relay socket number does it go into?

Nick

Toga

Hi Nick!

the relay is on socket R24 in the fuse box. I swapped it this morning with another one and no change!!! So the relay is probably not faulty.
( by the way in the RS model, the relay is behind the dashboard!)
I spent my morning taking note of all connections, wires color code, and what wires is connected with the others while I turn the light switch on. Now I printed the lights wiring diagram and try to find out where could be the fault.
I also jumped again the connections from the dimmer potientiometer, but there I still miss the 12v input so the problem is elsewhere.
On the otherhand, when I turn the light switch on, there is 12V input on the relay socket...
I'll keep you updated on my findings, but as I'm not electrician this could take a while

1pcarnut

The stock radio has uses a built in power source to light the radio. However, I understand that if the radio has been changed to a later model, 97 or newer, then to get nighttime illumination an external power supply is needed, the most common place to tap from is the ashtray light circuit. Might want to check and see if this was tapped into and has not separated since this is part of the circuit and can affect dash lighting.

Leon993

you may have a damaged cable that you are overlooking. this could involve you removing the instrument planel and inspecting them one at a time. Be patient, no matter what dont go to the dealer because they will suggest a massive replacement of parts that will make your wallet shrivle

iJeremy

Is the radio working currently?.. And if so, is the illumination on the radio as it should be? - Could actually be a fault in the electronic switch on the ignition barrel... VERY common on the 986/996 generation but I've even seen previous models suffer from this. It's in the same loop and would/could cause the issue.