Control units (Description): Description and operation (page 3 of 3)

Heated Windscreen Operation of the heated windscreen is controlled by the CCU and a non latching switch on the centre console. The switch contains a LED which illuminates while the heated windscreen is on. Power for the heater elements is supplied by a relay, on the inboard side of the E-box, controlled by the CCU. Two fuses next to the relay provide electrical protection for the heater elements.

When the heated windscreen switch is pressed, the CCU energises the heated windscreen relay, provided the engine is running, to connect a battery power feed to each of the heater elements. The feed to the RH heater element also provides the power feed to illuminate the LED in the heated windscreen switch.

The CCU de-energises the heated windscreen relay after approximately 5 minutes, when the switch is pressed again, or if the engine stops.

Tail Door Latch The tail door latch is operated by a tail door lock motor controlled by the CCU. When the CCU receives an open request from the tail door handle switch, it energises the tail door lock motor for 440 ± 40 milliseconds provided the vehicle is in the following configuration: l The door locking system is in the unlocked state. l The alarm system is disarmed. l Road speed is less than 3 ± 1 mph (5 ± 1.5 km/h).

The position of the ignition switch has no effect on the operation of the tail door lock motor.

Window Lift Power for side door window operation is supplied from the window lift relay and, on 5 door models, the auxiliary relay, both located in the passenger compartment fusebox. The CCU controls the relays, which are energised while the ignition switch is in position II and for approximately 40 seconds after the ignition is turned off. WINDOWS, DESCRIPTION AND OPERATION, Description.

Seat Heating Power for the seat heaters is supplied from the auxiliary relay in the passenger compartment fusebox. The CCU controls the auxiliary relay, which is energised while the ignition switch is in position II and for approximately 40 seconds after the ignition is turned off.

Daytime Running Lamps The daylight running feature is controlled by the CCU via two daylight running relays located inboard of the passenger compartment fusebox. The CCU switches the relays, to illuminate the dipped beams, side lamps, tail lamps, rear number plate lamp and side marker lamps, when the following conditions are met: l The engine is running. l Gearbox selector lever not in Park. l Headlamps not selected on.

The CCU and the daylight running relays are also used to operate the head/side lamps when they are selected on using the lighting switch on the LH column stalk. The lamps then operate as on non daylight running vehicles, and remain on when the gearbox is in Park and when the engine is switched off.

Self Test Mode The CCU can be put into a self test mode to enable the inputs and outputs to be tested for correct functionality without the need for TestBook/T4. To put the CCU into the self test mode the vehicle must be unlocked and disarmed, then the ignition turned on and the following sequence completed within 4 seconds: l Hold the rear fog guard lamp switch on. l Turn the ignition off. l Turn the ignition on. l Release the rear fog guard lamp switch.

On successful entry to the self test mode the CCU simultaneously operates the sounder and illuminates the courtesy lamps for 0.8 second.

When testing an input, e.g. a door open switch, on successful receipt of the input the CCU also simultaneously operates the sounder and illuminates the courtesy lamps for 0.8 second.