P1539

Schematic:

Schematic:

CIRCUIT DESCRIPTION
The PCM activates the A/C clutch relay when the PCM detects an A/C request. Voltage is present at both the A/C compressor clutch and the A/C clutch status terminal at the PCM when the relay is activated.

A DTC P1539 sets if the PCM detects a voltage on the A/C clutch status terminal when the system has not requested the A/C.

A short to voltage at any point in the A/C status circuit, or the A/C relay contacts are stuck, sets a DTC P1539.

CONDITIONS FOR RUNNING THE DTC
The A/C is not requested.

CONDITIONS FOR SETTING THE DTC
Voltage is detected on the A/C status circuit for more than 15 seconds after the PCM has disengaged the A/C clutch relay.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM stores the DTC information into memory when the diagnostic runs and tails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
^ Use a scan tool in order to clear the MIL/DTC.

DIAGNOSTIC AIDS
^ The A/C status circuit goes to the A/C compressor clutch and to the A/C clutch relay. Inspect all circuits going to these components.
^ For an intermittent condition, refer to Symptoms. Symptom Related Diagnostic Procedures

TEST DESCRIPTION

Diagnostic Chart:

The numbers below refer to the step numbers on the diagnostic table.
2. If the PCM detects a voltage on the A/C status circuit with the A/C OFF the scan tool indicates the A/C status as ON.
3. If the scan tool displayed YES in the RAN column and INT in the FAIL column, this indicates an intermittent condition is present. Inspect the A/C status circuit for an intermittent short to B+. Using the Freeze Frame and/or the Failure Records data aids in locating an intermittent condition. If you can not duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data determines how many miles since the DTC set. The Fail Counter and the Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that the PCM recorded. This isolates when the DTC failed.
4. The relay is shorted internally if the scan tool indicates that the test passed.