My headlights, tail light, windows,a/c etc not working

If all of your lights are working (high, low beam, tail lights etc) u may have an electrical short in the headlight switch circuit or a bad headlight switch

may be you should make a diagnostic and you can do it in a garage or you can do it by yourself if you want to do it by yourself you need some tools and you can find some good ones here: diyobd2.fr

If you have checked the fuses for those two circuits and they have power, the next step would be testing the headlight switch.

No. Dash lights being out could be a bad headlight switch, since the dash lights are routed through the headlight switch, not the dimmer switch. Park and tail lights also controlled by the headlight switch.

Sure sounds like your tail/dash/license plate fuse is blown.

im not sure what your talking about, it sounds like you want the wiring for the cluster, but this doesnt control brake,tail or headlights, the brake lights operate through the brake light switch and go through the signal light switch to power those up. the headlights and tail lights work through the head light switch, what system do you need, or what doesnt work.

Sounds like you have a bad ground at the tail light unit.
ie:when you put the brakes on(when lights off) it is getting the ground through the tail and head light filaments, and conversly as you switch the lights on you will be feeding 12v+ backfeed to the tail light unit,and therefore effectively switching both tail and brake lights off.

Hope this helps, and get back to me if you require further assistance

The relay has nothing to do with the tail lights, but replacing the switch sounds like a good idea. There's a nut holding it in place, see http://www.skandix.de/en/spare-parts/electrics/switches/switch-headlight/1027524/ to get an idea of the construction. And the price. This is not worth fiddling about unreliable workarounds...
In addition, if fuses 15 and/or 16 burn frequently there might be a problem with the tail light cabling.

Good luck
Ingo

I have had this happen and it is rare, but I have had a filiment burn out in a two filment buld and short to the other filiment. It does happen and I think this might be your problem, the only way to find it is a visual inspection of each bulb. I am sure many people will think this is crazy, but I have had the exact same problem, I had the schematics, tested the circuits,etc. and them by accident found a stop/blinker 1157 bulb that had done this exact thing. I hope this helps you, check the bulbs in your headlights also.

If you already check the dimmer definetly you will have to remove the dashboard area where the indicator is and replace those light bulbs they are tiny so careful and first check your auto parts store for correct number.luck!