Operation

OPERATION

Front Power Distribution

Feed from the positive battery terminal (C0192) is supplied to fuse 26 and fuse 53 of the passenger compartment fuse box (C0632) on an R wire. Fuse 26 (C0583) provides a constant battery feed to the wiper delay ECU (C0546) on an RW wire.

Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0099 on Td6 vehicles, C0028 on V8 vehicles) on an R wire. When the ignition switch is turned to the 'auxiliary' position, current flows across the switch (C0099 on Td6 vehicles, C0028 on V8 vehicles) to fuse 41 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 41 (C0586) provides an auxiliary ignition feed to the Body Control Unit (BCU) (C0660) on a PW wire, and the rain sensor (C0961) on a PR wire.

Rain Sensor

The rain sensor (C0961) is mounted on the upper edge of the windscreen. It is provided an auxiliary ignition feed from fuse 41 of the passenger compartment fuse box (C0586) on a PR wire, and is earthed on an NB wire. The rain sensor (C0961) provides information to the BCU (C0660) via the K bus on a WRY wire. This information is used by the BCU to determine optimum wiper operation for the prevailing conditions.

Steering Wheel Switch

The BCU (C0660) provides feeds to the steering wheel switches (C0278) on BW and BU wires. The steering wheel switch (C0278) is earthed on an NB wire. The BCU determines which function has been selected by the earth paths that are created by the switch. If slow wipe is selected, current on the BW wire flows across the switch to earth. If fast wipe is selected, current on both the BW and BU wires flows across the switch to earth. If intermittent wipe is selected, current on the BU wire flows across the switch to earth.

The steering wheel switch also contains a rotary potentiometer to control the intermittent wipe function. The intermittent wipe setting is interpreted by the BCU (C0661) from the feed returned from the switch (C0278) on a BG wire.

When the BCU (C0661) senses that wiper operation is required, it provides a feed to the wiper delay ECU (C0546) on an NU wire. The wiper delay ECU (C0546) is earthed on an N wire and provides two feeds to the wiper motor (C0546) on BG and BN wires.

Washer

If the steering wheel switch is pulled towards the driver, current flows from the BCU (C0660) to the steering wheel switch (C0278) on an NP wire, and then to earth on an NB wire. Sensing this earth, the BCU (C0662) provides a feed to the washer pump motor (C0008) on a B wire. Current flows across the washer pump motor (C0008) to earth on an N wire. The BCU powers the washer pump motor for as long as the switch is held in position, and also powers the wipers at slow speed.