P1546

Circuit Description
The PCM activates the A/C clutch relay when the PCM detects an A/C request signal. When the PCM activates the relay, voltage should be present at both the A/C compressor clutch and the A/C clutch status circuit at the PCM. The PCM monitors the A/C status circuit for voltage after the clutch is enabled. If the PCM does not detect a voltage this DTC sets.

Conditions for Running the DTC
The A/C is requested

Conditions for Setting the DTC
The PCM commands the A/C ON and the PCM detects no voltage on the A/C clutch status line for more than 5 seconds.

Action Taken When the DTC Sets
^ The PCM stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM disables the A/C.
^ 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 last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

Important:
^ Remove any debris from the PCM/TAC module connector surfaces before servicing the PCM/TAC module. Inspect the PCM/TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM/TAC modules.
^ For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter kit J 35616-A. Using this kit prevents damage to the harness/component terminals.
^ The following may cause an intermittent:
- Poor connections
- Corrosion
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
^ For an intermittent condition, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests the operation of the A/C compressor clutch. The PCM disables the A/C compressor clutch when this DTC is set.
3. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.
4. This step verifies whether the ignition voltage is available at the relay.
5. This step determines if the A/C relay is at fault or the A/C status circuit is at fault. If the A/C clutch engages, this indicates that the A/C Status circuit is OK.
6. If the A/C Status is displayed as OFF, this indicates the A/C status circuit is open between the splice and the PCM. If the A/C Status is displayed as ON, this indicates a faulty connection at the A/C compressor relay or a faulty relay.