Sunroof Operation, Troubleshooting, and Repair

System Description

The sunroofs on 944s are raised and lowered by two lifting arms at the rear edge of the roof. On cars made after February 1986, the lifting arms are operated by plastic gears (one for each lifting arm mechanism). The plastic gears have a small set of teeth which operate the lifting arms and a large set of teeth driven by a flexible cable. The cable is driven by the sunroof motor.

For cars produced before February 1986, there is a gear box between the two lifting arm mechanisms. This gear box has a single gear which moves the lifting arms via two short lengths of drive cable.

The sunroof drive motor assembly is located in the rear hatch area behind the vertical section of carpet on the driver's side of the car. On most cars the motor assembly will have a plastic cover held in place by six Phillips head screws.

The sunroof system uses a series of micro-switches to stop the lifting arms in different positions. On 1985.5 and newer cars the ignition is a three-position switch (OFF/0 — ACCESSORY/1 — ON/2). To operate the sunroof open or closed, the ignition must be in the ON (position 2). To release the lifting arms for sunroof removal, the ignition must be in ACCESSORY (position 1) on late cars or OFF on early cars.

Late cars Sunroof (February 1986 onward)

All sunroofs since February 1986 have three limit switches operated by a plastic cam attached to the sunroof drive cable. As the motor drives the cable the cam rotates.

• Cam position 1 (released): Lifting arms fully retracted for sunroof removal. Both Limit Switch I and II are made. This is the condition for removing the sunroof from the car.
• Cam position 2 (locked closed): Lifting arms partially raised, sunroof locked closed. Limit Switch II drops out to stop the motor.
• Cam position 3 (fully open): Sunroof fully raised. Limit Switch III stops the motor.

Caution: Over time, motor slip clutch torque tends to increase. When the lifting arms retract and contact the body, excessive torque can strip the teeth on the plastic sunroof gears. Periodic slip clutch torque verification is essential.

Early cars Sunroof (1982 to February 1986)

The early sunroof does not use a rotating cam. Instead, a guide rail attached to the motor extends rearward. A plastic dog on the end of the drive cable operates the two limit switches at the rear of the guide rail. The fully open position is controlled by a micro-switch mounted between the sun visors, operated by a tab on the front of the sunroof hatch.

The micro-switch between the sun visors also tells the system that the sunroof is installed. If the sunroof is installed with the lifting arms in the released position, the system will automatically move the lifting arms to the locked position when the car begins moving.

Normal Operation

Early cars: Turn ignition to ON. Push the console switch back (direction "A") to open; push forward (direction "B") to close.

1985.5 and newer cars: Turn ignition to ON (position 2). Push the console switch up-arrow to open; push down-arrow to close.

Removing the Sunroof

1. Retract the sunroof lifting arms: a. Early: Turn ignition to OFF. Press the sunroof switch in the back direction ("A") to retract the lifting arms. b. 1985.5 and newer: Turn ignition to ACCESSORY (position 1). Press the sunroof switch in the back direction (up arrow) to retract the lifting arms.

2. Release the two latches at the front of the sunroof.

3. From inside the car, push up on the back of the sunroof and slide it off the wind deflector and front guides.

Installing the Sunroof

1. Slide the sunroof hatch onto the wind deflector guides until it seats at the front of the sunroof opening.

2. Lower the back of the sunroof into the sunroof opening so it sits flush with the roof.

3. Engage the latches at the front of the sunroof.

Note: When raising the lifting arms from the retracted position, the arms should automatically stop at the locked closed position.

4. Engage the sunroof lifting arms: a. Early: Turn ignition to OFF. Press the sunroof switch forward (direction "B") to raise the lifting arms. b. 1985.5 and newer: Turn ignition to ACCESSORY (position 1). Press the sunroof switch forward (down arrow) to raise the lifting arms.

Sunroof Manual Operation

Early cars (1982 to February 1986)

1. Unclip the carpet on the driver's side of the hatch area to access the sunroof motor and cable drive assembly.

2. Below and to the left of the sunroof motor, find the manual operating tool attached to the cable guide by two wing nuts. Remove the tool.

3. Below and to the right of the sunroof motor, locate the slip clutch adjusting screw covered by a cap. Remove the cap and, using the tool, remove the adjusting screw.

4. Insert the tapered end of the tool into the threaded sleeve inside the screw opening. Turning counter-clockwise closes the sunroof; turning clockwise opens it.

5. When manual operation is complete, reinstall the adjusting screw and perform the slip clutch adjustment procedure.

Late cars (February 1986 onward)

1. Unclip the carpet on the driver's side of the hatch area.

2. Locate and remove the slip clutch adjusting screw cap below and to the right of the sunroof motor.

3. Behind the cap is a small lock nut and, behind that, a large nut (21 mm or 13/16″ spark plug socket). Turn this large nut clockwise to close; counter-clockwise to open.

Note: Since the slip clutch adjusting screw position is not altered during late cars manual operation, a slip clutch adjustment is not required afterward.

Sunroof Motor Slip Clutch Adjustment

Early Style (before February 1986)

The early slip clutch adjusting screw has a lock nut cemented at a preset distance (2.5 mm) from the screw head. Adjustment is only required if the screw has been removed for manual operation.

1. Remove fuse 9 from the Auxiliary Fuse Panel and connect an ammeter across the fuse block terminals.

2. Thread the adjusting screw into the slip clutch until the lock nut contacts the mounting surface; tighten slightly.

3. Turn the ignition on and operate the sunroof switch to the full open position. Check the motor current when the motor reaches its final drive position.

4. Tighten the adjusting screw until motor current reads 12–14 Amps. This may require loosening the lock nut.

5. When properly set, tighten the lock nut against the mounting surface and apply heavy-strength Loctite to the adjusting screw threads at the lock nut.

6. Disconnect the ammeter and reinstall the 25 A sunroof motor fuse.

Late Style (February 1986 onward)

• A — Checking torque nut (21 mm)
• B — Adjusting torque nut
• C — Lock nut

1. Open the sunroof approximately halfway. This protects the plastic gears during slip clutch testing.
2. Using a 21 mm socket and torque wrench, turn hexagonal nut A. The clutch should slip at 6 N·m4 ft·lb ± 0.5 N·m0 ft·lb. A value at the low end of specification (5–5.5 N·m4 ft·lb) is preferable to prevent future gear stripping.
3. Check the torque six times at 60° intervals through one full rotation of nut A — slip torque can vary across gear positions.
4. If adjustment is required: a. Loosen lock nut C. b. Turn adjusting nut B to set torque. Loosening B decreases torque; tightening increases it. c. Apply a small amount of Loctite 270 to the adjusting screw threads and tighten lock nut C to 15 ± 2 N·m1 ft·lb.

Troubleshooting and Repair Guide

Find your symptom below. Most electrical faults are isolated with the sunroof component electrical testing procedure in ELECT-18; mechanical faults (gears, drive cable, slip clutch) are handled here and in BODY-04.

Sunroof motor will not operate at all

Start with the fuses, then the electrical components:

• Bad fuse — Early cars (pre-Feb 1986): Fuse 6 main panel (relay), Fuse 9 additional panel (motor), Fuse 8 main panel (relay). Late cars (Feb 1986 onward): Fuse 1 (motor), Fuse 8 (relay).
• Electrical component fault — micro-switch between the sun visors, limit switches, main sunroof relay, console switch, directional relays, sunroof motor, or ignition switch. Isolate with sunroof component electrical testing (ELECT-18).

Arms retract to released but won't raise to locked

The lifting arms drop to the released (removal) position but will not come back up to locked-closed. Suspect the console switch, the micro-switch between the sun visors, Limit Switch 2, or Directional Relay 1. Test per ELECT-18.

Arms move but won't retract for removal

The arms cycle up and down but will not drop to the released position needed to take the sunroof off. Suspect the main sunroof relay, the console switch, or Limit Switch 1. Test per ELECT-18.

Raises to open but won't lower to locked

The sunroof raises to fully open but will not return to the locked-closed position. Suspect the console switch, Limit Switch 1, or Directional Relay 2. Test per ELECT-18.

Lowers but won't raise

The sunroof lowers but will not raise again. Suspect the micro-switch between the sun visors or the console switch. Test per ELECT-18.

Automatically raises when the car moves

The sunroof raises by itself once the car starts moving. This is Limit Switch 2 either bad or misadjusted. Test and adjust per ELECT-18.

Motor turns but nothing happens

The motor runs but the lifting arms do not move. Either the slip clutch torque is set too low, or the drive gears have failed — stripped plastic sunroof gears on late cars, or a damaged gear box on early cars. Replace the plastic sunroof gears (BODY-04) or the gear box, and reset the slip clutch (see the slip clutch adjustment above).

Arms not level or raise unevenly

The two lifting arms are out of sync. Suspect a worn drive cable or the plastic sunroof gears. Replace the plastic sunroof gears (BODY-04) or the drive cables as necessary.