19. August, 2020

Porsche 944 sunroof electronics

I’ve had some issues with my Porsche 944 sunroof. Clarks Garage has good instructions for the mechanical issues, but at the electrical side it falls short. I’m posting my findings so far:

Please go through the guide in Clarks Garage FIRST. I’m not covering any of the areas that he already covered.

The relay:
The relay pin numbers do not correspond to the pin numbers in the socket.
relay socket pin -> relay pin
1 -> 2 (sunroof SW pin1)
2 -> R (IGN lock via F36)
3 -> 30 (Positive via F8)
4 -> A (cruise control pin1)
5 -> 1 (passenger door pin1)
6 -> 15 (from instrument panel IIRC…)
7 -> 31 (GND)
8 -> 3 (Sunroof SW pin2)
9 -> 4 (sunroof SW pin5)

Checking for voltages in the relay socket:
Pin7 is GROUND
Pin3 is always +12V
Turn the key one click and get +12V to pin2
Turn the key one more click and get +12V to pin6
I believe pin5 gets 12V when the car is locked (haven’t checked)
I believe pin4 gets 12V when the car is moving (haven’t checked)

If these voltages do not show up you have a problem with wiring, a blown fuse or a problem with your ignition switch.

bench-testing the relay:
In this case I’ll refer to the numbers printed on the relay itself.

ground to pin31 , 12V to pin30. Check all remaining pins for voltage, you should have none.
Add +12V to pin R, you’re supposed to get voltage at pin8 – I got +10V, and I don’t know if you should be getting 10 or 12.
Add +12V to pin 6 (15 at the relay) +10V disappears from pin3 and +12V appears at pin2

I believe adding 12V to pin 1 or A should give +12V at pin9, but I’m not sure of wether it should affect (remove) any voltage to pin 8 or 2. I believe what this does is tell the motor to lock the sun roof in place if the car is moving or is locked. I’ll update this when/if I figure out mine.


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