S5 TII

I've been having this issue since I owned the car. The dash gauges would always read nearly 2 volts less than charging, and the charging voltage would be less than 14 volts.

Today I just started pulling fuses while the car was running. When I pulled the sunroof fuse, the dash voltage jumped to 14.2 and the charging voltage 14.6.

I started tracing the sunroof circuit and found something interesting. There are two paths from the fuse box in the kick panel. One goes to a switch that runs up alongside my mouse belt (the actual sunroof power wire). And the other disappears into the dash harness hidden behind the tach and plastics. Does anyone know what that wire is for? Both of them from the Fuse panel are Green with an orange stripe.

I looked in the wiring diagram and it doesn't show a split on that circuit (before the switch).

I think everything is working on my car still, but I'm just curious what that other wire does.

Checkout the wiring diagram here:
http://s8.photobucket.com/albums/a47...nt=Sunroof.jpg

 

Nearly all of the fuses feed more than one circuit, otherwise there'd be dozens of them. You can see what each fuse feeds in the list on the FSM Body Electrical chapter or in the Electrical Wiring Schematic in the Wiring Diagrams chapter.

The 15A SUNROOF fuse also feeds the ABS control unit. If you don't have ABS that second wire won't lead to anything.

Are you sure the problem isn't related to the sunroof?

 

Well I do have ABS, but there doesn't seem to be an issue with it.

 

That fuse also feeds AAS and the air bag system (on cars equipped with those):



But I personally doubt that the fuse in or out would have anything to do with the gauges being under powered. Rather that playing around down there, pushed a loose plug in, or made a better contact.