C1735

CIRCUIT DESCRIPTION
The compressor is switched ON and OFF via an ELC compressor relay which is controlled by the CVRSS module. The control module circuitry provides a switched path to ground (low-side drive) whenever compressor activity is required. This drive circuit is also continually monitored to determine if the voltage level agrees with the commanded state.

CONDITIONS FOR SETTING THE DTC
^ The DTC is set when the CVRSS module sees a high voltage condition at pin C15 during a compressor ON-state.
^ The DTC will turn HISTORY when the CVRSS module no longer senses a high voltage condition at pin C15 while the ELC compressor relay output drive is in an ON-state.

ACTION TAKEN WHEN THE DTC SETS
^ The compressor relay output drive is disabled for the remainder of the ignition cycle.

CONDITIONS FOR CLEARING THE MIL/DTC
^ Use the scan tool.
^ Refer to the CLEAR RSS CODES feature.

DIAGNOSTIC AIDS
This fault condition is detectable only when the compressor relay output is commanded to the ON-state, which occurs during the Air Replenishment Cycle (ARC) and whenever an upward correction is necessary. The control module expects to see a low voltage condition during the ON-state.
Only electrical problems with the compressor relay coil circuit are flagged. The compressor motor problems and pneumatic leakage problems do not set a DTC, but the CVRSS module shuts the compressor relay off if there is no progress, or if excessive run times occur. Recovery is not attempted until the ignition is cycled OFF, then ON.

TEST DESCRIPTION

IMPORTANT:
^ Do not back probe the sensors, actuators, or any sealed connectors.
^ When all the diagnostics and repairs are complete, clear the DTCs and verify the operation.

The number(s) below refer to the step number(s) on the diagnostic table.
2. This step checks for an internal open circuit condition in the ELC relay.
3. This step checks for a short to voltage condition in circuit 321.

Page 1 Of 2:

Page 2 Of 2:

DTC C1735 COMPRESSOR RELAY SHORT TO BATTERY