DIRECTION INDICATOR/HAZARD WARNING LAMPS ............................... 4

Instrument Pack

The instrument pack (C0230) acts as a gateway, relaying CAN messages to and from different components throughout the vehicle as follows:

Pressure Sensor

The pressure sensor is located in the high pressure A/C line adjacent the compressor, and replaces the more traditional trinary pressure switch. The instrument pack (C0230) provides a 5 V reference voltage to the pressure sensor (C1257) on a UO wire. The pressure sensor (C1257) is provided an earth path via the instrument pack (C0230) on a PB wire.

The pressure sensor (C1257) provides the instrument pack (C0230) a signal feed on a UG wire. The value of this signal feed is dependent upon the pressure within the A/C system. The instrument pack relays this information to the ECM via the CAN BUS. The ECM uses this to determine the pressure within the A/C system, enabling it to carry out the following tasks: To provide a safety cut-out function if the pressure within the A/C system goes either too high or too low. To control the speed of the cooling and condenser fans via the cooling fan control unit. To help control engine idle speed.

Evaporator Temperature Sensor

The evaporator temperature sensor is used to ensure the evaporator doesn't freeze. The instrument pack (C0230) provides a feed to the evaporator temperature sensor (C0417) on a GO wire. The sensor (C0417) is earthed on a B wire. The instrument pack relays evaporator temperature sensor status to the ECM via the CAN BUS. NOTE: The ECM also uses the evaporator temperature sensor signal in conjunction with the pressure sensor signal to help control engine idle speed.

Cooling Fan Control Unit

Fusible link 5 of the engine compartment fuse box (C0573) provides a constant battery feed to the cooling fan control unit (C0208) on an NG wire. Fuse 4 of the engine compartment fuse box (C0575) provides a feed to the cooling fan control unit (C1680) on an NK wire when the main relay in energised (see above). The cooling fan control unit (C0208) is earthed on a B wire.

To control cooling fan and condenser fan speed, the ECM (C0331) provides the cooling fan control unit (C1680) a Pulse Width Modulated (PWM) signal on a UW wire. The frequency of the pulses supplied by the ECM determines the speed the cooling fan control unit will drive the cooling fan and condenser fan motors.

The cooling fan control unit interprets the PWM signal provided by the ECM as follows: If a PWM signal of between approximately 12 % and 87 % is received by the cooling fan control unit, it will not power the cooling fans. If a PWM signal of 87 % or over is received by the cooling fan control unit, it will provide a feed to the cooling fan (C0005) and condenser fan motors (C0280) on SU wires. An earth path is provided for the cooling fan (C0005) and condenser fan motors (C0280) by the cooling fan control unit (C0701) on a pair of PS wires. If a PWM signal of less than 12 % is received by the cooling fan control unit, it assumes a fault has occurred and powers the cooling and condenser fan motors as described above. If a continuous voltage is received by the cooling fan control unit, it assumes a fault has occurred and powers the cooling and condenser fan motors as described above.

Fresh/Recirculated Air

Fuse 4 of the passenger compartment fuse box (C0586) provides an ignition feed to the fresh/recirculated air motor (C0006) and the fresh/recirculated air switch (C0750) on G then LGS wires. When the switch is the normal (released) position, it provides an earth path for the motor (C0006) via a Y wire. The motor will open the recirculation flap, allowing the A/C system to use air drawn from outside the vehicle.

If the fresh/recirculated air switch is pressed, it provides an earth path for the motor (C0006) via a K wire. The motor will now close the recirculation flap, allowing the A/C system to use recirculated air. The switch is mounted on the centre console, adjacent the A/C master switch, and is earthed (C0750) on a B wire.