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Removal, Inspection and Replacement of the Sun Roof Motor

The basic instructions for the removal of the sunroof motor can be found here.  This however, gives little detail on identifying a common problem with these motors or how to synchronise the motor with the sunroof prior to refitting.

I wrote the following instructions based on my own experience in dealing with a defective motor.

It is worth noting at this point that a No. 2 cross-head screwdriver and a No. T30 star-head screwdriver is required to remove the overhead console and the motor.
 

Once removed, the plastic cover-plate can be easily removed by unscrewing the two No. T20 star-head screws and carefully releasing the four plastic retaining clips.

On inspection, you will see that the main nylon drive cog is driven directly by the metal spiral drive shaft of the electric motor. This alone means that any undue stress on the unit is liable to damage the teeth of the nylon cog, slowly but surely wearing a concave slot in the nylon.

Risk of damage to the unit can be greatly reduced by regular maintenance and greasing up of the sunroof, ensuring it slides freely.

Andrew H has provided excellent detail on maintaining the sunroof.

It’s also worth checking the condition of the splines which interface with the sunroof gear as these too are prone to stripping.

I’m sure there’s a thermal overload device built into the unit, but it takes considerable excessive load before tripping to reduce unwanted stop-starting of a sunroof which may not be freely running.

If you’re acquiring a second hand motor from a breakers yard, it’s worth taking the necessary tools to strip the motor and checking on the condition of the drive gears. If there’s any wear as described, then it’s probably seen the best of its life and not worth wasting your money on.

Because the plastic cover plate acts as bearing points for the drive gear, it’s probable that the gears will fall out of alignment when you remove it. This is nothing to worry about as it’ll square back up on reassembly.

One excellent feature of this unit it that its sun roof stop positions (fully open, fully closed and fully tilt) are controlled by travel limit switches which are operated by a cam system located under the other cog driven by the main drive gear, but this feature does mean that the motor has to be properly synchronised with the position of the sunroof or the motor will attempt to drive past its stop positions, never properly close and may damage the drive gear.

Replacing the Motor

Provided the drive gear is in good condition, reposition the cogs and replace the plastic cover plate, making sure the locating pins fit properly into their holes in the casing and the cogs fit properly in their locating (bearing points). Never operate the unit with the cover plate removed or damage to the drive gear will result.

Because it’s virtually impossible to manually push the sunroof to the closed position with any degree of accuracy, I found the best way was to push the sunroof fully open, then connect up the motor to the wiring harness and the sun roof switch. Don’t actually fit the motor yet.

If you disconnected the battery during removal, reconnect now.

Next comes the tricky bit.

Synchronise the Motor

1. With the motor turned so you are looking at the cover plate face (see photo above), watch the main drive gear and press and hold the ‘sunroof open’ button. The gear should rotate clockwise, continue to hold until it stops. Release the button, then press it again. If the cog does not rotate, then the probability is that the motor is in its fully open position. If it does rotate (still clockwise) continue to hold the button until it stops again and the motor will be in the fully open position.

2. It’s worth confirming position and that the unit is functioning properly by running it through all positions, so press and hold the ‘close sunroof’ button and the gear should rotate anti-clockwise approximately 9 revolutions and stop. Release the button – This should be the fully closed position.  Press the close button (tilt button) again and the gear should complete approximately one anti-clockwise rotation and stop – Fully tilted position.

3. Now return the motor to the fully open position by pressing the open button, (one clockwise rotation and stop). Release and press again. (9 clockwise revolutions and stop.)

4. The motor will now be in the fully open position. Refit, taking care when locating the motor drive gear onto the sunroof drive gear, secure with all 3 screws and test for proper operation.  If the sunroof operates correctly now then you have finished the task.

5. If the sunroof does not completely close before it stops, then this is a good indication that the sunroof control cables are stretched, and depending on how much they are stretched, you may wish to consider replacement. You will need to make a minor adjustment to the sunroof / motor synchronisation though.

6. Press and release the sunroof close button in very short ‘bursts’ until the roof is completely closed. (You may have to ‘joggle the roof into position using the open/close buttons). Then remove the motor and press the open button to return it to its fully closed position. (This should be far less than one clockwise rotation of the main drive gear).

7. If in doubt, press the open button again – approximately 9 clockwise rotations to fully open, then press the close button – 9 anti-clockwise rotations to fully closed.

8. Refit the motor & test again. The roof should operate properly, though if the control cables are stretched, then the roof will never completely open or completely tilt.
   
   This sounds far more complicated than it is, but worth doing properly. If you get it wrong you may strip another gear.

Andy Brown