newmexicomatt

the lights that illuminate the HVAC controls, *****, clock, etc on the center console aren't working. The only one that works is the little light in the ash tray. Does the auto shift selector light up? Would this be a fuse or light bulb type issue? Any thoughts would be appreciated. Its a '91 S4

Ed Scherer

I would expect that your gauge back-lighting in the pod would be on that list, too (but only when the parking or headlights are on).

I would have said, "check fuse #9", but since the ashtray light is working (which is on that fuse, along with the other stuff you mentioned), that points to the dimmer rheostat on the left side of the steering column. It is often not very reliable. Roll it back and forth a few times and see if anything changes. You could also try a jumper across the two terminals on the dimmer rheostat, which will have the effect of running all the instrument lighting at full intensity.

Oh... and, unless you or a previous owner has rigged up back-lighting for the shift selector, it is not illuminated.

newmexicomatt

the dash pod lights work fine and the rheostat does too...I'm thinking the POS stereo head unit was most likely hacked into the situation making the lights inoperable

Ed Scherer

Does that head unit light up with the other instrumentation lighting?

If the pod instrument backlighting dims with the rheostat when the parking/headlights are on, that does mean that the rheostat is OK. Seems kind of hard to believe, though, as most of the other stuff that's not working is wired in before that connection.

You'll probably need to start tracing wiring. All the stuff you mentioned will have a BK/BL (black with blue stripe) wire providing the brightness-controlled-by-the-dimmer rheostat current. Some of these might be daisy-chained, so a break in one place might take down multiple lights.

I think the instrument lighting on your '91 is wired mostly the same as my '90 (the one for which I have diagrams available). If you look at Sheet 2, you'll see that there are three points in the diagram around coordinates F-4: a "2" with a box around it, a "3" with a box around it, and the connector T5 all involving connections of BK/BL wires.

newmexicomatt

thanks Ed for this info

hwyrnr

I just did the lights in the center console of my 84. For my case it was just the lights burnt out in the HVAC and the clock. My ashtray light worked and my gear selector light worked, and is not an aftermarket setup. I don't know about a 90 model gear selector. But the bulb for the HVAC and the clock were the same. I believe it is a 12v 1.2 watt bulb. the one for the clock I was able to access by removing the passenger side carpeted trim panel. And to remove the HVAC I followed the write up on the AC relay repair. With the side panel removed you can see under to the gear selector to see if there is a bulb.

When you remove the HVAC and get your bulb back in do yourself a favor and check for continuity on the two micro switches for the temp setting by depressing the little button on the switch, and the petientiometer before you put it back together. I had to remove and reinstall the HVAC 3 times due to doing something to the max cold setting micro switch.

Good luck.
James

newmexicomatt

thanks James, it sure looks like my gear shift selector should be illuminated.

Mrmerlin

NOTE your gear shift is not illuminated

NOTE if the HVAC is not lighted then the bulb has burned out.

Remove the HVAC and AC panel then take the covers off the head unit,
then fish the bulb from the center of the unit,
refit a new bulb,
plug it in to make sure it lights up prior to assembling the unit.

hwyrnr

you may want to get new slider ***** before you pull the unit out. If they are old you may break them while removing. Considering they are not that much it would be nice not to have to wait on them in the mail. You can get the correct bulb and sliders from one of the RL vendors, I got mine from Pelican.

James

Mrmerlin

^^^^ thats a good idea if the sliders are loose.
NOTE you will not be removing the sliders to replace the bulb,
the bulb is removed by taking the HVAC top and bottom covers off,
then finding the wires that go to the bulb holder,
the holder pushes in from the rear in the center of the unit.

hwyrnr

Mrmerlin is correct, I just found since I was replacing the sliders it was easier for me to do the bulb from the face. I tried to remove from the back but mine didn't want to come out to easy and was afraid I may tear up something else.

Also since I had the face off I put some reflective ducting HVAC tape in the top bottom and the back of the area that would be lit. I didn't cut to perfection but just enough to see if it would illuminate a little better. I don't know if it helped or not since the bulb had been burnt out since I got the car. But I did it and it seems bright enough.

Also if you do replace the sliders the little tension spring that is in there I had to cut the 2 inner post of the spring to let the new slider go through. I did tis with a cut off wheel on a dremel tool. Or you can just get new tension springs as well when you get the sliders

ltoolio

That's pretty much a given