P1546

CIRCUIT DESCRIPTION
Ignition voltage is supplied directly to the A/C compressor clutch relay. The powertrain control module (PCM) controls the relay by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be near 0 volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage.

CONDITIONS FOR RUNNING THE DTC
^ The ignition voltage is between 9.0-18.0 volts.
^ The engine speed is more than 80 RPM.
^ The PCM driver is activated.

CONDITIONS FOR SETTING THE DTC
^ The PCM detects an improper voltage level on the output circuit that controls the A/C relay.
^ The condition is present for at least 30 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM stores the failure records. The A/C compressor clutch is disabled.

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.

TEST DESCRIPTION

Steps 1-4:

Steps 5-14:

The numbers below refer to the step numbers on the diagnostic table.
3. Listen for an audible click when the A/C compressor clutch relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
4. Tests for voltage at the coil side of the A/C compressor clutch relay. The 10-Amp fuse supplies power to the coil side of the A/C compressor clutch relay.
5. Verifies that the powertrain control module is providing ground to the A/C compressor clutch relay.
6. Tests if ground is constantly being applied to the A/C compressor clutch relay.
7. Tests for a short to voltage or an open.
13. Perform the programming procedure for the powertrain control module.