Sunroof Component Testing

Tools

• Multimeter
• Jumpers / test leads
• External 12 VDC voltage source

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Testing the Micro-Switch Between the Sun Visors

Introduction

A small micro-switch is located beneath a triangular-shaped cover between the sun visors. On early 944 sunroof systems (1982 – February 1986), this switch stops the sunroof in the fully raised position. On later systems it functions as a backup to Limit Switch III.

This micro-switch is a common failure point. A failed switch prevents the sunroof from operating electrically in the open direction — either from the locked position to open, or from the released position to locked. It should not prevent operation in the close direction.

Removing and Replacing the Micro-Switch

1. Release and remove the sunroof hatch. If the system cannot be operated electrically, use the manual release procedure described in the Sunroof Operation, Troubleshooting, and Repair procedure.

2. Carefully remove the triangular flap from the sunroof mount. Use a small flat-tip screwdriver or plastic spatula and pry gently on each side — the flap is clipped in and the clips or tabs can break if force is excessive.

3. Remove the Phillips head retaining screw from the mount and press the mount off the wind deflector bar.

4. If replacing the micro-switch, unsolder the wires from the old switch and solder them to the new switch.

Checking the Micro-Switch for Proper Operation

For the sunroof to operate in the open direction, the micro-switch must be closed and remain closed.

1. Check the switch as follows:

   a. Remove the sunroof hatch. b. Press on the flap covering the sunroof mount. c. An audible click should be heard. If no click, remove the flap as described above. d. Depress the micro-switch operating lever — listen again for a click.

   e. If no click is heard, check the switch electrically (next step).

2. Electrical check:

   a. Lower the mount containing the micro-switch from the roof panel (per removal procedure above). b. Connect an ohmmeter across the two terminals. Should read infinite resistance (∞ / OL). c. Depress the operating lever. Should read < 1 Ω. d. If the switch fails, replace it.

Note: The micro-switch is operated by a tab on the front of the sunroof hatch. If the tab is bent and fails to depress the switch fully, the switch will not stay closed. Test with the roof installed and closed — if pressing upward on the tab produces an audible click from the switch, the tab is too flat. Remove the roof and bend the tab upward slightly until it reliably closes the switch with the roof installed.

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Main Sunroof Relay Testing

1. Access the sunroof switch or plug:

   Early 944s (small console switch): Remove the switch from the top of the console using a flat-tip screwdriver or spatula.

   Late 944s (larger switch):

   a. Slide both hands into the storage pocket below the radio and press outward on the sides while pulling straight out. This exposes two Phillips head screws — remove them.

   b. Pull the ash tray straight up out of the console. Remove the two Phillips head screws at the back of the console.

   c. Lift the console insert. Removing the radio trim piece may be needed. d. Release the two tabs on each side of the console switch using small flat-tip screwdrivers inserted under both tabs simultaneously — this releases all four tabs at once. Slide off the plug.

Note: On early cars, checks are performed on the back of the switch with it connected to the harness. On late cars, checks are performed on the disconnected plug.

2. Check main relay output voltages:

   a. Early 944: Insert the key (do not turn on). Late 944: Turn ignition to ACCESSORY. b. Check for ~12 VDC at terminal 2 of the switch/plug. c. Turn the ignition to ON (both early and late). d. Check for ~12 VDC at terminal 1 and confirm voltage at terminal 2 is no longer present.

3. If correct voltages are not present, remove the sunroof main relay and check supply voltages at the relay socket:

   • Early 944 (pre-1985.5): Relay is the second from the left on the top row of the main relay and fuse panel.
   • Late 944s: Relay is G18 on the Central Electric Panel.

   a. Early: Insert key (no ignition). Late: Turn to ACCESSORY. Check for ~12 VDC at terminal R of the relay socket. b. Turn ignition ON. Check for ~12 VDC at terminals A and R.

4. If supply voltages are correct but output voltages are absent, the main relay is faulty and must be replaced.

5. If output voltages are present, the main relay is functioning sufficiently for normal sunroof operation.

Note — Speed-dependent raising: The lift arms raise from retracted to locked when vehicle speed exceeds 5 km/h (3 mph). This can be checked by verifying ~12 VDC at terminal 5 of the console switch plug at the required speed. On early 944s, this signal comes from a hall sensor on the left front wheel; on late 944s, from the electronic speedometer signal via a hall sensor in the transaxle.

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Limit Switch Testing

Introduction

The sunroof limit switches are a frequently suspected but less frequently confirmed cause of sunroof problems.

• Early 944 sunroofs: Limit switches are located at the back of the drive cable guide rail. Limit Switch 1 is on top, Limit Switch 2 is on the bottom.
• Late 944 sunroofs: Limit switches are located almost directly above the sunroof motor. Limit Switch I is on the bottom, Limit Switch II on the top.

Wire Connections

Switch	Late Model	Early Model
Limit Switch I	1 — black/red; 2 — green/red; 4 — black	3 — black/red; 1 — green/red; 2 — black
Limit Switch II	1 — grey/green; 2 — not connected; 4 — grey/black	3 — grey/green; 1 — not connected; 2 — grey/black
Limit Switch III	1 — yellow; 2 — yellow/black; 4 — not connected	N/A

Late Sunroof Limit Switch Positions and Readings

Sunroof Position	Limit Switch I	Readings	Limit Switch II	Readings	Limit Switch III	Readings
LOCKED	Closed	1–4 < 1 Ω; 1–2 ∞	Open	1–4 ∞; 1–2 < 1 Ω	Open	1–4 ∞; 1–2 < 1 Ω
OPEN	Open	1–4 ∞; 1–2 < 1 Ω	Open	1–4 ∞; 1–2 < 1 Ω	Closed	1–4 < 1 Ω; 1–2 ∞
RELEASED	Closed	1–4 < 1 Ω; 1–2 ∞	Closed	1–4 < 1 Ω; 1–2 ∞	Open	1–4 ∞; 1–2 < 1 Ω

Early Sunroof Limit Switch Positions and Readings

Sunroof Position	Limit Switch 1	Readings	Limit Switch 2	Readings
LOCKED	Closed	2–3 < 1 Ω; 1–3 ∞	Open	2–3 ∞; 1–3 < 1 Ω
OPEN	Open	2–3 ∞; 1–3 < 1 Ω	Open	2–3 ∞; 1–3 < 1 Ω
RELEASED	Closed	2–3 < 1 Ω; 1–3 ∞	Closed	2–3 < 1 Ω; 1–3 ∞

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Sunroof Console Switch

Removing the Late Console Switch for Testing or Replacement

1. Disconnect the sunroof switch plug (follow the console disassembly steps described in the Main Sunroof Relay section above).

2. If removing the switch from the console insert, press the retaining tab on each side of the switch using a small flat-tip screwdriver and pull outward. Often releasing only one side and swinging the switch out is sufficient; if resistance is felt, release the second tab.

3. When reinstalling, slide the switch straight into the holder on the back of the console insert.

Console Switch Testing

The function and terminal labelling are identical for early and late console switches.

• Switch depressed in the BACK (A) direction: Resistance between terminals 2–5 and 1–3 should each be < 1 Ω.
• Switch depressed in the FORWARD (B) direction: Resistance between terminals 2–6 and 2–4 should each be < 1 Ω.

If correct readings are obtained, the switch is good.

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Directional Relay Testing

A faulty directional relay typically prevents sunroof operation in all directions, though it is possible for one bad relay to affect only one direction. Both relays should be tested simultaneously.

1. Remove both directional relays from the terminal block near the sunroof motor. The relays can be difficult to extract — pry gently along the bottom edge if needed.

Caution: Terminal 87 (closest to the outside of the car on later systems) on each relay always has 12 VDC present. Use care when prying.

Note: Relay terminals are labelled on the bottom of each relay.

2. Connect an ohmmeter between terminals 30 and 87a. Resistance should be < 1 Ω.
3. Connect a 9 V battery to the relay with positive on terminal 85 and negative on terminal 86. An audible click should be heard. Resistance between terminals 30 and 87a should now be ∞. Resistance between terminals 30 and 87 should be < 1 Ω.
4. Disconnect the battery from the relay. Another click should be heard. Resistance between terminals 30 and 87 should return to ∞.
5. If all readings are correct, the relay is functioning normally.

Also check the voltage supply to the relay terminal block and verify grounding of wiring connections.

On early 944 sunroof systems (insert the ignition key, ignition not required to be on on later cars): both terminal 87s should read 12 VDC to ground; the 86 terminals and 87a terminals should read < 1 Ω to ground.

If the 87 terminal voltage is absent:

• Later sunroof cars: Check Fuse #1 on the Central Electric Panel.
• Early sunroof cars: Check Fuse #9 on the Additional Fuse Panel; if good, check Fuse #6 on the Main Fuse Panel.

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Sunroof Motor Testing

Test the sunroof motor only if all other component tests are satisfactory and the motor will not run. Disconnect the sunroof motor plug connector and connect an external 12 VDC voltage supply directly. If the motor does not run, it is faulty.

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Ignition Switch Testing

If the main sunroof relay supply voltage is absent, the ignition switch or its wiring may be faulty.

Early Sunroof Cars

1. Insert the key into the ignition switch.
2. Check for ~12 VDC at terminals A and R on the main sunroof relay socket.
3. Turn the ignition to ON. Check for ~12 VDC at terminal 15 on the relay socket.

Late Sunroof Cars

1. Turn the ignition to ACCESSORY.
2. Check for ~12 VDC at terminals A and R on the main sunroof relay socket.
3. Turn the ignition to ON. Check for ~12 VDC at terminal 15 on the relay socket.