Sunroof Component Testing – 2.5L NA

Overview

This procedure tests and troubleshoots the electrical components of the sunroof system on a Porsche 944 (8-valve engine configuration), including the micro-switch, main relay, limit switches, console switch, directional relays, motor, and ignition switch. Proper testing ensures the sunroof operates correctly in open, closed, and locked positions. This guide is specific to the 83-85.5 (Pre-85.5) and 86-88 (85.5 Onwards) variants, addressing differences in components and procedures.

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Tools Required

• Multimeter
• Jumpers/Test leads
• External 12 VDC voltage source (e.g., 9V battery for relay testing)
• Small flat-tip screwdriver (3mm / 1/8 inch)
• Phillips head screwdriver (size PH2)
• Plastic spatula (optional for gentle prying)

Parts Required

• Micro-switch (if replacement needed): 944 613 121 00
• Main sunroof relay (if faulty): 944 615 101 00
• Console switch (if faulty): 944 613 115 00 (Pre-85.5) or 944 613 116 00 (85.5 Onwards)
• Directional relay (if faulty): 944 615 102 00
• Fuse (if needed): 944 610 911 00 (for fuse #1, #6, or #9)

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Sunroof Operation, Troubleshooting, and Repair

Step-by-Step Procedure

Step 1: Test and Replace the Micro-Switch Between Sun Visors

1. Release and remove the sunroof hatch. If the sunroof cannot be operated electrically, manually release the lifting arms. Follow this link to ensure this step – Sunroof Operation, Troubleshooting, and Repair – is followed accurately.
2. Carefully remove the triangular flap covering the micro-switch using a small flat-tip screwdriver (3mm / 1/8 inch) or plastic spatula. Gently pry on both sides to release the flap from its clips, avoiding damage to the clips or flap tabs.

3. Remove the retaining screw from the micro-switch mount using a Phillips head screwdriver (size PH2), then press the mount off the wind deflector bar.

4. Press the flap or micro-switch operating lever and listen for an audible click. If no click is heard, proceed to electrical testing.
5. For electrical testing, connect a multimeter (set to ohms) across the micro-switch terminals. It should read infinite ohms (∞) when not pressed.
6. Depress the micro-switch lever; the multimeter should read less than 1 ohm. If the switch fails this test, replace it with a new micro-switch (944 613 121 00).
7. If replacing, unsolder the wires from the faulty micro-switch and solder the new switch in place.

8. Check the sunroof hatch tab that operates the micro-switch. With the roof installed and closed, press upward on the tab. If you hear a click, the tab may be bent too low. Remove the roof and slightly bend the tab upward to ensure it closes the micro-switch.

Step 2: Test the Main Sunroof Relay

9. (Pre-85.5) Remove the small console switch from the top of the center console using a small flat-tip screwdriver (3mm / 1/8 inch) or plastic spatula to gently pry it out.

10. (85.5 Onwards) Disconnect the sunroof switch plug as follows:

a. Remove the storage pocket under the radio by pressing outward on its sides and pulling it straight out.

b. Remove the two Phillips head screws exposed under the pocket.

c. Remove the ashtray from the center console by pulling it straight up, then remove the two Phillips head screws at the back of the console.

d. Lift the console insert, removing the radio trim if necessary.

e. Release the four plastic tabs on the console switch plug using two small flat-tip screwdrivers (3mm / 1/8 inch) to slide under the tabs simultaneously, then slide the plug off.

11. Test the relay output voltages:

a. (Pre-85.5) Insert the ignition key without turning it on. (85.5 Onwards) Turn the ignition to the ACCESSORY position.

b. Using a multimeter, check for approximately 12 VDC at terminal 2 of the sunroof switch/plug.

c. Turn the ignition to the ON position for both variants.

d. Check for approximately 12 VDC at terminal 1 of the sunroof switch/plug. Verify that voltage at terminal 2 is no longer present.

12. If voltages are incorrect, locate and remove the main sunroof relay. (Pre-85.5) It’s the second relay from the left on the top row of the main relay and fuse panel. (85.5 Onwards) It’s relay G18 on the central electric panel.
13. Test the relay socket supply voltages:

a. (Pre-85.5) Insert the ignition key without turning it on. (85.5 Onwards) Turn the ignition to the ACCESSORY position.

b. Check for approximately 12 VDC at terminal R of the relay socket.

c. Turn the ignition to the ON position for both variants.

d. Check for approximately 12 VDC at terminals A and R of the relay socket.

14. If supply voltages are correct but output voltages are incorrect, replace the main sunroof relay (944 615 101 00).
15. (Optional) Test the relay’s speed-sensing function for lifting arms:

a. Check for 12 VDC at terminal 5 of the console switch plug while the car moves faster than 5 km/h (3 mph).

b. (Pre-85.5) Raise the front of the car and spin the left front wheel to simulate speed. (85.5 Onwards) Drive the car or raise the rear and rotate the transaxle.

Step 3: Test the Limit Switches

16. Locate the limit switches. (Pre-85.5) They are at the back of the sunroof drive cable guide rail, with Limit Switch 1 (top) and Limit Switch 2 (bottom). (85.5 Onwards) They are above the sunroof motor, with Limit Switch I (bottom), Limit Switch II (top), and Limit Switch III.
17. Test the limit switches using a multimeter set to ohms, following the resistance readings for each sunroof position (LOCKED, OPEN, RELEASED) as per the tables below:

a. (Pre-85.5) Early Sunroof Limit Switches:

– LOCKED: Limit Switch 1 (2-3: <1 ohm, 1-3: ∞), Limit Switch 2 (2-3: ∞, 1-3: <1 ohm)

– OPEN: Limit Switch 1 (2-3: ∞, 1-3: <1 ohm), Limit Switch 2 (2-3: ∞, 1-3: <1 ohm)

– RELEASED: Limit Switch 1 (2-3: <1 ohm, 1-3: ∞), Limit Switch 2 (2-3: <1 ohm, 1-3: ∞)

b. (85.5 Onwards) Late Sunroof Limit Switches:

– LOCKED: Limit Switch I (1-4: <1 ohm, 1-2: ∞), Limit Switch II (1-4: ∞, 1-2: <1 ohm), Limit Switch III (1-4: ∞, 1-2: <1 ohm)

– OPEN: Limit Switch I (1-4: ∞, 1-2: <1 ohm), Limit Switch II (1-4: ∞, 1-2: <1 ohm), Limit Switch III (1-4: <1 ohm, 1-2: ∞)

– RELEASED: Limit Switch I (1-4: <1 ohm, 1-2: ∞), Limit Switch II (1-4: <1 ohm, 1-2: ∞), Limit Switch III (1-4: ∞, 1-2: <1 ohm)

18. If any switch fails the resistance test, replace it (consult a parts supplier for specific limit switch part numbers).

Step 4: Test the Console Switch

19. (85.5 Onwards) Remove the console switch for testing:

a. Remove the storage pocket under the radio by pressing outward on its sides and pulling it out.

b. Remove the two Phillips head screws exposed under the pocket.

c. Remove the ashtray by pulling it straight up, then remove the two Phillips head screws at the back of the console.

d. Lift the console insert, removing the radio trim if necessary.

e. Release the four plastic tabs on the switch plug using two small flat-tip screwdrivers (3mm / 1/8 inch) simultaneously, then slide the plug off.

20. Test the console switch using a multimeter set to ohms:

a. Depress the switch in the BACK (A) direction. Check for less than 1 ohm between terminals 2-5 and 1-3.

b. Depress the switch in the FORWARD (B) direction. Check for less than 1 ohm between terminals 2-6 and 2-4.

21. If the switch fails the test, remove it from the console insert by depressing the tabs on both sides with a small flat-tip screwdriver (3mm / 1/8 inch) and replace it with a new switch (944 613 115 00 for Pre-85.5 or 944 613 116 00 for 85.5 Onwards).

Step 5: Test the Directional Relays

22. Remove both directional relays from the terminal block near the sunroof motor. Gently pry with a small flat-tip screwdriver (3mm / 1/8 inch) if needed, avoiding the live terminal 87.
23. Test each relay:

a. Connect a multimeter (set to ohms) between terminals 30 and 87a. It should read less than 1 ohm.

b. Connect a 9V battery (positive to terminal 85, negative to terminal 86). Listen for a click. The resistance between terminals 30 and 87a should now be infinite (∞).

c. Move the multimeter to terminals 30 and 87. The resistance should be less than 1 ohm.

d. Disconnect the battery. Listen for a click. The resistance between terminals 30 and 87 should now be infinite (∞).

24. If a relay fails, replace it with a new directional relay (944 615 102 00).
25. Check the relay terminal block:

a. (Pre-85.5) Insert the ignition key. (85.5 Onwards) No key needed.

b. Verify 12 VDC at both terminal 87s to ground and less than 1 ohm from terminals 86 and 87a to ground.

c. If voltage at terminal 87 is incorrect:

– (Pre-85.5) Check fuse #9 on the additional fuse panel. If good, check fuse #6 on the main fuse panel.

– (85.5 Onwards) Check fuse #1 on the central electrical panel.

Step 6: Test the Sunroof Motor

26. If the motor does not run and all other tests pass, disconnect the sunroof motor plug connector.
27. Connect an external 12 VDC voltage source to the motor terminals to test operation. If the motor does not run, replace it (consult a parts supplier for the motor part number).

Step 7: Test the Ignition Switch

28. If the main sunroof relay fails testing, check the ignition switch:

a. (Pre-85.5) Insert the ignition key. (85.5 Onwards) Turn the ignition to the ACCESSORY position.

b. Check for approximately 12 VDC at terminals A and R on the main sunroof relay socket.

c. Turn the ignition to the ON position.

d. Check for approximately 12 VDC at terminal 15 on the relay socket.

29. If voltages are incorrect, inspect the ignition switch or wiring for faults (consult a parts supplier for ignition switch part numbers).

Post Procedure Checklist

• Verify the sunroof operates smoothly in all positions (LOCKED, OPEN, RELEASED).
• Check for any electrical faults or blown fuses.
• Ensure all components (flaps, switches, relays) are securely reinstalled.
• Test the sunroof at a speed above 5 km/h (3 mph) to confirm the lifting arms lock correctly.
• Inspect for loose connections or damaged wires.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• Youtube