aprotogerellis

Hya,

I've been having trouble with fuse 1 for a while. It fuses the sunroof and some of the electrics for the rear hatch.

Last year the fuse used to blow every couple of weeks. So I asked around (https://rennlist.com/forums/924-931-...t-working.html) and the conclusion was that I had to correct the clutch on the sunroof motor.

I did this and for half a year all was good. Then, last weekend, the fuse seemed to have gone. Here we go again I said...

This time however the moment I replace the fuse it blows. Even with the keys out the moment the fuse makes contact it blows...

I use a standard 25A one.

Any ideas on how I can go about diagnosing this one?!

Thanks!
Alex

aprotogerellis

Hya,

A bit of an update... Fuse 1 is meant to power the sunroof mechanism and some of the electrics for the rear hatch.

So, I disconnected both and it still blows...

Any suggestions on where to start diagnosing?!

All help really appreciated!

Calmchaos

Are there any bare wires up under the dash?
Maybe if you can wiggle your way down there and look straight up to under the fuse box you'll find something to suspect.

The wires that power these pieces run above the e-brake handle, past the rear seat. Maybe a short in there?
Only guesses.

Yarf

What year and model is your car?

NCporsche

I have all 4 workshop manuals for the 944s including the electrical volume which includes wiring diagrams.

What year and model is your car?

aprotogerellis

Thanks guys!

its a 944 turbo, 1986...

Yarf

There are 2 thumb screws inside the corners of the fuse/relay panel, loosen these screws and lift up the fuse/relay assembly to expose the connectors on the bottom. Release connector "J", pin 35 is the 12 VDC feed for the Sun Roof lift motor and the Rear Hatch release motor. With connector "J" disconnected replace Fuse #1 it should not fail. If F1 holds then there is a short in the wire in pin 35 of connector "J". Tell us what the results are.