DESCRIPTION AND OPERATION 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. This signal is relayed by the instrument pack (C0230) to the ECM (C0331) via the CAN-BUS on YB (High) and YN (Low) wires. The ECM uses this signal to determine the pressure within the A/C system, enabling it to carry out the following tasks: l To provide a safety cut-out function if the pressure within the A/C system goes either too high or too low. l To control the speed of the cooling and condenser fans via the cooling fan ECU. l 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 the temperature reading to the ECM (C0331) via the CAN BUS on YB (High) and YN (Low) wires. NOTE: The ECM also uses the evaporator temperature sensor signal in conjunction with the pressure sensor signal to help control engine idle speed. For more information on CAN messages, refer to the Communication Databuses section of the System Description and Operation Workshop manual.
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FREELANDER 02MY
