sprie

After driving the car in the day light for a while, I had to drive the car one morning in the dark and discovered that when the side or headlights were on, the dash instrument light didn’t work: completely dark (except for the Digi dash at the bottom). The centre console lights (e.g. HVAC, clock etc) worked fine.

I have done some investigations, and it shows odd/inconsistent behaviour. On occasion, when I start the car, the dash lights work (and the dimmer **** works) but then after a couple of seconds, the dash lights stop working and won’t come back. Whilst I know this could be a bad connection somewhere, I am thinking this is not the issue as:

a) it never starts “off” and then comes “on”, it is sometimes when I start that it comes on

b) there is no flickering on/off.

So, I am wondering if this is a symptom of an electrical component somewhere that is on its last legs?

I have seen that there is a “Resistor Instrument Lights” on the wiring diagram (at D22 on sheet 4 for 1990), but I have seen a part number of 928 616 110 00 and information that this resister lives next to the brake pedal and that it has an impact on the starter motor – so I am confused as to whether this resistor if it were faulty could be the cause of my dodgy dash lights. I have also seen information that there is a light sensor behind the dash (which would be a struggle to access), not sure if this could be the cause of the issue.

Any guidance appreciated.

joejoe

Check if wire has come off dimmer, I think if one wire off lights don't work (dash lights) ( i may be incorrect)

ZEUS+

. The dash light potentiometer is on sheet 2, E2. Check for loose connections, power in and out. Found a thread with info on the resistor.https://rennlist.com/forums/928-foru...-resistor.html

jschiller

I had the same problem. The fix was to replace the resistor (16) high up above the pedals:

I managed to get it out, but it was so frustrating getting the nuts off the damn thing and impossible to get back on, I just ziptied it back in place. Part # 92861611000 as I recall.

Read this thread before you start to make sure the symptoms are the same. You will NOT want to change the resistor if it doesn't fix the problem.
https://rennlist.com/forums/928-foru...-question.html
Good luck!

davek9

When was the last time you cleaned and de-oxidized all the fuses ?

Dave K

sprie

Hi Dave. i did remove the board recently and clean everything up (all the connections, fuses, relays) as part of trying to sort out an issue i had with the headlights.

sprie

i suspect i am going to have to do this. I have already removed the dimmer and tried replacing with a bypass cable, but i had the same symptoms (i.e. it worked for a second or two then nothing), so i think the issue lies elsewhere, and this resistor is the next place to look.