P1546

Circuit Description

Output Driver Modules (ODMs) are used by the PCM to turn on many of the current-driven devices that are needed to control various engine and Transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding on. ODMs have the capability of diagnosing each output circuit individually. DTC P1546 set indicates an improper voltage level has been detected on the output circuit which controls the A/C compressor control relay.

Conditions for Running the DTC

^ The ignition is on.
^ A/C is requested.

Conditions for Setting the DTC

^ An improper voltage level has been detected on the output circuit which controls the A/C compressor control relay.
^ The above conditions are present for at least 30 seconds.

Action Taken When the DTC Sets

^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

^ A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ DTC can be cleared by using a scan tool.

Diagnostic Aids

Check for the following conditions:

Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

^ Poor terminal connection.
Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Diagrams.
^ Damaged harness.
Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault.
^ Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table:

1. The Diagnostic System Check prompts you to complete some basic checks and store the freeze frame and failure records data on the scan tool.
2. Listen for an audible click when the relay operates. Command both the on and off states. Repeat the commands as necessary.
3. Tests for voltage at the coil feed side of the relay.
4. Verifies that the PCM is providing ground to the relay.
5. Tests if ground is constantly being applied to the relay.
12. The PCM utilizes Electrically Erasable Programmable Read only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.