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This part of site is an attempt to organize and add to the web resources for the Rover SD1 to form a cohesive and easily usable guide for those of us without easy access to expert repair and/or advice. It is not offered in any way as a definitive source and we take no responsibility for any errors that may exist.

Electric Windows

Electrically operated windows are fitted as standard on the 3500 and as on option on the 2600.
The system comprises the drivers and passengers control switches (1) and motor unit to operate each window (2), a rear-window isolator switch (3), two control relays (4) an a thermal circuit breaker (5)

The drivers control is by four non-latching rocker switches mounted on the centre console.
Each rear window can also be operated by a similar switch mounted on it's door.
The window lift mechanism and it's motor are build as an assembly which should not be separated.
This assembly must be treated with great respect. The motor is very powerful. The 2 relays, 1 to control the front-windows the other to control the rear windows are located behind the passengers glovebox.
The drivers has a push-push-switch which prevents rear window operation by de-energizing the rear window control relay.
This prevents tempering by children in the rear seats. This is the window lift circuit.

Let us make it easier to understand and see how it operates.
When the ignition is switched on, the 2 control relays, yellow, are energized. They supply current, shown in red, to the six control switches, green.
By depressing any of these six control switches, the circuit through the appropriate motor, blue, is completed.

The motor rotates and the window is raised or lowered as selected. Internal wining of the control switches allows reversal of the window lift motors.
This is a cheat by reversing the polarity of the power supply. Depressing the front of a switch will raise the window, depressing the rear of the switch will lower the window.
The drivers control switches on the left supply current to the rear windows through the close contacts of the rear passengers control switches on the right. When the rear window isolator switch (yellow) is open the rear window control relay (purple) is de-energized and the supply to the rear-window circuit is cut.
Window overtravel is prevented by a mechanical stop on the motor drive plate.

If the control button is not released when the stop is reached, a self-resetting thermal switch inside the motor casing will cut the power supply.
If the total system becomes overloaded, the thermal circuit breaker located behind the passengers glovebox, shown here in blue, will trip and power through the contacts of both relays (yellow) will be cut.
However the relays will remain energized. In the event of this happening the unit must be reset manually be depressing the red button.

The system may look complex but by adopting a methodical approach to troubleshooting, time and effort will be saved. Be warned, larking a bite can be dangerous. In the event of a total system failure, first check that the supply voltage is reaching the thermal circuit breaker. Then with the ignition on check the supply at both relay coils. Now disconnect the thermal circuit breaker output and measure the voltage at the terminal.

If the reading is zero depress the reset button.
If the reading remains low or zero the circuit breaker is faulty and must be replaced.
If however the voltage is correct reconnect the output lead then recheck the voltage. If it is dropped to zero the circuit breaker has tripped probably due to a short circuit. This must be found and rectified.
If the failure is only partial and both front-windows have failed check the appropriate relay. If both rear-windows have failed, first check the control relay, then the isolator switch. The two relays are identical and can be tested by swapping there connecting plugs. If only one window fails to operate, check it's control switch and connecting leads before suspecting the motor.
If it is a rear-window both control switches must be checked. The motor assembly can be reached by removing the door trim pad.
But before removing the motor ensure that the fault is not mechanical or even icing in cold weather.



© rwp aug. 2004