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How they work

The 37.4 x 12.6-inch electrically operated synchronised door and window takes around five seconds to open or close, and is hung from its' toothed drive belt which is supported by a mechanism situated behind the rear wing panel beneath the door button.

The front of the door is not supported except when latched up or down. All movement of the door is controlled by an electric motor turning a toothed drive wheel, which lowers or pulls the drive belt. When the door is open or closed, it engages a lock-shaft which turns to operate the latch, and a microswitch which disconnects power from the motor. The door then rests on the lockshaft, with no strain on the belt or the motor.

The door is hung from the base-plate to which all the mechanism is fixed. The door can only be adjusted horizontally by addition or subtraction of shims from behind the front door track and the door mechanism mounting plate at the rear. This is never normally required, and when built from new, the shim value in mm is painted on the chassis next to each mounting bolt.

Open Window

Closed Window

Sequence of events

When the door button is pressed, (assuming window and door are closed)

  1. A shaft behind the door button pulls a rod, Door motor and window motor are engaged, door and window opens together.
  2. The rod releases the mechanical catch of the door, the catch activates the 1st step of the microswitch, instructing the door control unit “door is released”.
  3. The second stage of the microswitch gives the 'motor-on' command to the door control unit, to start the motor (alternate up and down after initial setting).
  4. The motor moves the belt and the door moves.
  5. The window lifter is controlled by the door control unit. Except when opened manually, as the window motion is controlled by the manual movement of the door, incases such as flat battery, it is possible to open door and window by hand.

If door is open

  • When the button is pressed, the door motor lifts the door until it is closed (locked in the catch) and then the window motor engages to close the window.

If window is open

  • When button is pressed, only the door motor engages. If the window is partially open, it’s the same as if it is fully closed. Only difference is, that the window goes to its last known position when you close the door.

In an Emergency

Assumming door is unlocked.

  • The door/window can be opened manually, unlock the door using the key, the latch will be released as the mechanism is mechanical, you should hear a click sound, indicating door is released. Simply push down to open, this may require some pressure.
  • If door is open, simply grad the handle and pull upwards, the door and window will close as there is is no resistance from the motor preventing this action. This action will require considerable force as the door is heavy, but should operate smoothly until it gets to the top.
  • Locking the door will take a big effort when it gets to the top, but with a great pull, it should latch and allow you to lock it in place. MIND YOUR BACK!!


If the window is closed, the first part of the door lowering action is to use the window motor to partially lower the window a little bit, as well as the main door motor to drop the door.

When the door is raised, the last bit of the operation is to raise the window by the window motor.

HOWEVER. IF the window is stuck, the whole thing appears to work just fine, except that as the door is raised that last little bit, it puts an extra strain on the system to force the window into its seal (if the hood is up), at the same time as raising the door onto it's latch.

Sometimes the door lift motor can't cope, and the door will fall a bit, only for the motor to try again.

The thing to check is: Make sure that the windows work OK. It is not uncommon for the passenger window to get stiff (due to lack of use), make sure that the window operation is OK, it will save strain on the door lift mechanism. both the lift arm and motor may need lubrication. (remove bodywork side panel to get it this lot).

NOTE: You cannot replace the microswitch on its own and you cannot access the bits you need to cure a microswitch problem without removing the door.

Window Adjustment

If you driver side electric window has started to behave erratically. when the window switch is pressed the window only moves an inch or two and then stops. If the switch is released and pressed again, it will move another step of an inch or two.

There is an 'anti-trap' systen which is designed to stop children getting trapped in the window.

This will cause the window to stop operating if there is a resistance to movement (it is activated by a couple of relays). If the mechanism has got stiff, then this will cause the window to stop/start.

Try lubricating the window slides with PTFE spray (dry-lube). Take off the rear wing and lower body panel to access the window motor, and clean off all the old grease and re-lubricate the runners and gears. The 10 yr old grease has probably hardened in this last cold weather, and is causing a partial siezure.

Please note that although the door may appear to work properly, if the window is stiff, then operation of the door and window will put extra strain on the door belt - because it will have to lift the door and the window without the assistance of the window motor. This could lead to failure of the door belt.


The most important part of the door assembly is arguably the toothed belt, also the most likely to fail. Its hard to estimate the shelf life of a toothed belt as there are some cars with the original belts and some have had several. It depends upon mileage, usage, or whether something is causing unnecessary strain shortening its lifespan.

The main service pointers are:

Toothed Belt

The toothed belt can be spotted beneath the door button, (behind the plastic guard with the broom fibres). Or by removing the trim at the top and look down. This should give a clear indication of belt condition, as the threads will be showing. Although not essential, this belt is normally changed if your having the door serviced.


Probably the most important part of a service, as this area is exposed to the elements. A considerable amount of dirt gathers in this area and covers everything, so cleaning is essential to long term preventative maintenance.

Clean everything, the plate, the bars, linkage, pins, gliders, wherever you see dirt, rust, gunge, caked on grease, clean it.

Then lubricate gliders.

Check plastic gliders

These are at the end of the window lifter arm and run inside the greased channels, they tend to create a cocktail of grease and dirt. They also reduce in size over time, so lookout for wear and tear, you may notice increased noise as a result.

Check Locking pins

These also wear as they are plastic, check, clean, replace if damaged.

Control Unit

To remove the Control Units, slide driver´s seat forward and open the battery flap.

  1. Control unit for right door
  2. Control unit for left door

Bend retainers to the side and pull control unit forward, unlock and pull off the plug.

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Wiring Diagram

doors.txt · Last modified: 2014/05/09 09:50 by zadmin