HondaCivicForum.com - instrument cluser lights not working: dimmer switch / wiring diagrams?

Hi

I just purchased a 1991 honda civic hatchback with an after market stereo.

First off, all the fuses are installed and in good condition.

The instrument cluster (NOT the seatbelt, warning lights, etc, just the dials) lights do not work.

Rear defrost button does not light up. Too hot out to tell if it actually works.

Online I learned of a black / red with silver speckled line which comes from the wiring harness, and is often cut in order to light up an after market stereo.

This wire had a connector on it, as did a few other wires which were hanging freely. The stereo was wired as indicated by the diagram printed on the stereo body. I didn't see any "stereo dimmer" wires which might have been cut from the regular wiring harness.

I discovered this loose wire, tested it to ground and it lit up when I turned on the headlamps. Grounded it through a test pen and the pen lit up when I turned the headlamp light control.

So I grounded this wire. and checked to see if the cluster lights lit up, they did not. Adjusted the dimmer switch, nothing happened.

I got a Chilton's manual and looked online for wiring diagrams, but nothing I have found shows the network of wires from the battery/alt to the fuse boxes, wiring harness to the various instruments and appliances in the vehicle.

At this stage I feel I ought to replace the dimmer switch and perhaps the defrost switch which is located right next to it. But I'm not sure what the wiring does between the dimmer switch, the console and the wiring harness.

QUESTIONS: Are there any decent wiring diagrams which might help me out in this situation?

Should grounding the red/ black/ silver speckled wire have done anything?

Is it likely that this is just a dimmer switch issue?

Any other observations or suggestions?

any insight appreciated, thanks!