P1539

CIRCUIT DESCRIPTION
The powertrain control module (PCM) activates the A/C clutch relay when the PCM detects that A/C has been requested. When activated, voltage should be present at both the A/C compressor clutch and the A/C compressor clutch supply voltage circuit at the PCM.

A DTC P1539 sets if the PCM detects voltage on the A/C compressor clutch supply voltage terminal when the system has not requested the A/C. A short to voltage at any point in the A/C compressor clutch supply voltage circuit, or the A/C relay contacts being stuck, also sets a DTC P1539, which is a type C DTC.

CONDITIONS FOR RUNNING THE DTC
- The ignition is turned ON.
- A/C is not requested.

CONDITIONS FOR SETTING THE DTC
The PCM detects voltage on the A/C compressor clutch supply voltage circuit for more than 15 seconds after the PCM has disengaged the A/C clutch relay.

ACTION TAKEN WHEN THE DTC SETS
- The PCM will not illuminate the malfunction indicator lamp (MIL).
- The PCM records the operating conditions at the time the diagnostic fails.
- The PCM stores this information in the Failure Records.
- The multifunction display (MFD) in the instrument cluster will display a message at key-on and key-off.

CONDITIONS FOR CLEARING THE DTC
- The DTC will become history if the PCM no longer detects a failure.
- The history DTC will clear after 40 fault-free ignition cycles.
- The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
The A/C compressor clutch supply voltage circuit goes to the A/C compressor clutch and to the PCM from the A/C clutch relay. Inspect all circuits going to these components.

TEST DESCRIPTION

Step 1 - 8:

The numbers below refer to the step numbers on the diagnostic table.
3. Verifies the condition is present.
4. Determines if the A/C compressor clutch relay is at fault.
5. Determines if the PCM is at fault or the A/C compressor clutch supply voltage circuit is at fault.