Porsche Enthusiasts Club Forum

Can anyone explain the workings of the hebedach/radio relay on my square dash 944 (p/n 944 615 103 00) ? I'd like to be able to test it on the bench, and also to bypass it to test the rest of the sunroof circuit. It's currently the prime suspect in my sunroof's failure to open (microswitches checked OK as per Clark's Garage), but I don't want to have to splash out the £35 or so which seems to be the going rate for one on eBay unless mine is definitely at fault. I also have an issue, which may or may not be related, with the radio being permanently live.

That relay sends the live feed when you put the key in the ignition and supplies the live that allows the sunroof arms to retract, thus removing the panel.

The radio live often fails on the relay and then people source another live

Thanks - my understanding from the wiring diagram is that pin "30" is permanently live, pin "R" becomes live when the key is inserted in the ignition (early car, remember) and then pins "A" and "15" become live when the key is turned to the first position. Pin "31" goes to earth. Is that all correct ?

As far as the radio is concerned, supplying 12v to pin "R" should enable the feed from pin "30" to pin "1" and thence the radio.

12v to pin "R" should also switch the feed (from which pin ?) to pin "3" but then 12v to pin "A" (or "15" ?) should switch it from "3" to "2". What's the reason for this - the handbook says nothing about the operation of the sunroof open/closing - what can be done to the sunroof with the key in that cannot be done with it switched on (or vice-versa) ? And what does pin "4" do ? Clark's manual refers to "the correct output voltages" but isn't specific about what they should all be.

hi there,
did you manage to fix your radio and sunroof relay issue? i have an issue with mine, I have 12v to pin 30, a good ground at 31, 12v to pin R when the key is inserted, however my radio relay doesn't click on and send power to the radio. i have tried three different relays and none of them have made it work.
any ideas what could be wrong? is the sunroof side of the relay possibly causing my issue?

cheers
tom

I just took a live from elsewhere Tom.