So I know that at some point in my car's life while it was owned by someone else, that they did some weird stuff and hacked up some wiring that I see under the hood.
Now, I have had the stock radio/cassette deck in my car the whole time I have had it. One strange thing is that to have my instrument panel lights on, I had to have the stereo turned on.
Yesterday I upgraded to a nice pioneer head unit, and now my instrument panel lights won't turn on and I can't think of anything to fix this.

Any suggestions would be greatly appreciated, Thank you.

 

I wonder if the lights were pulling their ground through the headunit.

 

That would've been a weird re-wire, but yeah that could be the cause.

 

If I were to find a wiring diagram, would I be able to wire up a simple switch to power on the dash cluster lights ?

 

Yeah it's possible. Find the Hot and the ground on your diagram and run them through a toggle. Or find these wires, and hook them up where they are supposed to go, and everything should work like normal.

 

i say get the diagram and wire it according to that, ive run into a few wire nightmare with my car as well....including a hidden cb radio under the dash......

 

I removed a garbage bag full of wiring and components that were dormant in my car. Mostly the remnants of remote locks/starter and security systems. Luckily, they used wire taps to splice into the electrical system for almost everything. Only had to fix a few things.

 

yeah the previous owner of my car apparently liked wire so much there were just unneccesary lengths of it lol and he was a big fan of pigtail/electrical tape method, personally its soldering gun and shrink tubing for me cuz it looks alot cleaner

 

Scotty, you can find a pinout for the 90-92 cluster here: http://www.austinthirdgen.org/index.php?pid=19
Scroll halfway down.

There is only one wire that illuminates the gauges (marked "Illumination" in the diagram) but there are multiple grounds on the cluster. I have a better diagram at home so I can look and tell you which ground is for the lights as well.

You can find the right wires behind the cluster and test them with a light or voltmeter to see whether you're missing the power or the ground.

Or have you found out anything?

Lou

 

Thanks very much for all the input, tomorrow being my day off I plan to look into all this.
I have a voltmeter but I dont really know how to use it but if there is only a power and a ground for the illumination then I guess it won't be too hard to figure out.
I already have the kneepad dropped and have had the cluster out before, but It would be easier to look in by removing the dash pad right ?

 

Ok, I checked last night for you and all the grounds on the C2 (drive side) connector are (partially) used for illumination.
On the C1 (passenger side) connector, pin #5 is used for illumination as well.

You cannot access the wires behind the cluster from the top, you need to go from behind. Or remove the cluster.

Hmmm, after re-reading your post, I have a stupid question: have you checked the INST LPS fuse yet? It powers the illumination in the vehicle (instrument cluster, A/C controls, radio).

Hope this helps.
Lou

 

ok, so I got my cluster pulled out, now I need to know how to test with a test light. Do I need to have the key on? Do I touch the wire or the pin with the test light? Where is a good place to ground the test light? For the grounds (C1 pin 5, C2 pins 2, 7, and 12), how do I know if they are good? Will the test light just light up?


Sorry for all the noobishness and thanks again for all the help.

 

Have you checked the INST LPS fuse yet?

You can try grounding the test light on the steering column bracket and/or bolts. Or whatever metal bracket/bolt is nearby. Then use the tester's tip to carefully touch pins that you are interested in. Make sure you don't slip and short something out, it can happen easily with a round tip (happens to the best of us!).

No need for the key to be on, the lights are on a separate circuit.

Once you determine that you have good power to pin 13, you can clip the alligator clamp onto that pin and (with the park lamps on) touch the tip of the tester to each ground. If the grounds are good, each one of them will light up.

Hope this helps.
Lou

 

Yes the inst lps fuse is good as are all others, is this connector supposed to be connected to something ? It branches off from the light switch wire cluster

 

Fog light switch, don't worry about it on your RS.

Lou

 

hey now, some RS's got fog lights from the factory. Mine apparently did, even though i've never bothered to take my front grill off to see them. I got the rpo.

 

ok so I tested number 13 and Ive got no power to it. So what should I do next?

 

Check the fuse with the test light. If the fuse has power on both sides, the problem is between the fusebox and the instrument cluster connector, in a wire.

If the fuse has no power on either side, the problem is either in the dimmer (part of the headlight switch) or in the wires.

If the fuse has power only on one side, try a different fuse and clean the contacts too.

Are all your other interior illumination lamps working when you turn the park lamps on? Like the heater controls, automatic shifter etc.

Diagram here: http://www.austinthirdgen.org/mkport...ts_dimming.jpg

Hope this helps.
Lou

 

so I popped in a new light switch for laughs and.... Now my dash lights work!!

Thanks again lou your always very helpful!

 

Glad to hear you found it!

Lou