P1546

Diagnostic Chart:

CIRCUIT DESCRIPTION

When the PCM detects that A/C has been requested, the PCM will activate the A/C clutch relay. When the relay has been activated, voltage should be present at both the A/C compressor clutch and the A/C clutch status circuit at the PCM. For the A/C system schematic refer to A/C Controls - C60 or A/C Controls - C67 and C68

CONDITIONS FOR SETTING THE DTC

The PCM has commanded the A/C ON and no voltage is detected on the A/C clutch status line for more than 5.0 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The DTC will be stored in the PCM memory when the diagnostic runs and fails.

^ The Malfunction Indicator Lamp (MIL) will not illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

^ A last test failed (Current DTC) will clear when the ignition is cycled and the diagnostic runs and does not fail.

^ A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

^ PCM battery voltage is interrupted.

^ Using a Scan tool.

DIAGNOSTIC AIDS

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to 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 were noted. This will isolate when the DTC failed. For intermittents, refer to Symptoms. Testing and Inspection

TEST DESCRIPTION

Number(s) below refer to step numbers on the diagnostic table.

2. A problem that may prevent the compressor from engaging may or may not cause a DTC P1546.

3. If the scan tool displays that the A/C Status is ON, indicates that the status circuit is OK.

4. Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to 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 were noted. This will isolate when the DTC failed.

5. Checks whether ignition voltage is available at the relay.

6. Determines if the A/C relay is at fault or the A/C status circuit is at fault. If the A/C clutch engages, indicates that the A/C Status circuit is OK.