Dash light wiring disaster!

[ScoupeS12]

Spent about three hours looking at the dash lights this afternoon. To no avail.

I had a good look at the wiring diagram before I left...but the car's a mile from the computer...so I couldn't do a too and fro!

I've got 12volts at both the fuses i presume are for dash lights "ILL LAMP" and "METER BACK UP LAMP"

At the stereo end (none fitted so simple wiring test!) 12v switched (ign ACC) from the pink wire, and 12v illumination from red with a white stripe.

At the dimmer there is a good ground, the ACC switch (pink) is 12v with ignition on and the red with white stripe has voltage out varying with the potentiometer in the dimmer switch

In the back of the dash there are 12v to both illumination wires (red with white stripe) and all four (IIRC) grounds are good. There is also 12v at the bulb holders if you remove one at a time.

There is also a strange black "wire" comming from the most Offside light pictures below (tiny red arrow in the top photo)...which is not connected to anything





So 2 things:

1. What is that black cable out of the back of the dash and should it be connected to anything?

2. Any ideas on where to look next on my hunt to make them light up again?

Cheers