Body control unit (Electric seats): Description and operation

The BCU controls the wiper motor frequency of operation via the IDM when intermittent wipe or wash is selected. The front intermittent wipe option features five different intermittent delay periods. The shortest delay period is 3 seconds and this is increased by 2 second increments up to a maximum delay of 11 seconds. The desired delay period for the front wipers is set by the position of the rotary switch located on the wiper column stalk.

The rear wiper switch is located on the instrument pack cowl and is latched when pressed. The rear wiper electric motor is located in the tail door. The rear wiper operation is controlled according to a programmed strategy via the BCU and the IDM. The BCU also checks for a signal from either the reverse lamp switch located in the vehicle gearbox (manual gearbox models) or the gear position switch (automatic gearbox models) for operating the rear wipers when the vehicle is in reverse. The rear wiper and washer only operate when the ignition switch is in position II.

The front and rear washer pumps and the headlamp powerwash (where fitted) are also controlled through the BCU. The washers are operated from electric pumps attached to the washer reservoir located in the left hand wheel arch. The front wash switch is located on the wiper column stalk and is pulled towards the steering wheel to select the washer function. When the front washers are operated, the wipers are also activated for three full cycles. The rear wash switch is located on the instrument pack cowl. The BCU programme can be configured in one of two modes of operation: l No wiper operation when the wash switch is pressed. l Wiper action after an initial delay of 400 ms.

Headlamp wash is activated by the BCU via the IDM and operates when the headlamps are on and the front washers function is selected.

Electric seats

The BCU controls the logical operation of the electrically operated front seats. Two modes of operation are available: SEATS, DESCRIPTION AND OPERATION, Description - electric seats. l Electric seat adjustment is enabled if the ignition is on or the driver's door is opened for a short time period. l Electric seat adjustment is enabled if the ignition is on and the driver's door is closed.

The seats are operated by four electric motors which control the seat cushion rear up/ down, the seat cushion front up/ down, seat cushion forward/ rearward and seat squab recline. The electrically powered lumbar adjustment in each seat is operated by a single motorised air pump and a solenoid located on the seat squab frame. The air pump inflates a cushion in the seat squab and the solenoid operates a valve to deflate the cushion. The seat squab and cushion may also contain heater elements to provide heated seat operation.

The switches for electrically operated seats are located either side of the centre console.

Direction indicators and hazard warning lamps

The direction indicator lamps are operated from a three position direction indicator switch on the left hand, steering column stalk. The BCU only allows the lamps to work as direction indicators when the ignition switch is in position II. The BCU also controls the lamps to operate as hazard warning lamps and as a visual warning for the anti-theft system, in which cases all lamps flash simultaneously irrespective of the ignition switch position.

System control of the direction indicators and hazard warning lamps is provided by the BCU operating with the IDM and two electronic relays located in the passenger compartment fuse box. The IDM and relays are integral parts of the passenger compartment fuse box and cannot be serviced individually. The serial data bus is used for communication of status and operation requests between the BCU, IDM and instrument pack.

The hazard warning lamps are operated from a latching pushbutton switch located on the fascia.

All direction indicator/ hazard warning lamp bulbs are rated at 5 Watts.