Refer to
A/C Compressor Controls
and to
HVAC Compressor Control Schematics
in HVAC.
Circuit Description
Output driver modules (ODMs) are used by the powertrain control module (PCM) to turn ON many of the current-driven devices that are needed to control the 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. |
| • | The system voltage is between 9.0 and 18.0 volts. |
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 stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
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.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
The Powertrain On-Board Diagnostic (OBD) System Check prompts you to complete some basic tests and store the Freeze Frame and Failure Records data on the scan tool.
-
Listen for a click when the relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
-
Tests for voltage at the coil feed side of the relay.
-
Verifies that the PCM is providing ground to the relay.
-
Tests if ground is constantly being applied to the relay.
-
The PCM uses electrically erasable programmable read-only memory (EEPROM). If the PCM is replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | ||
Does the relay turn ON and OFF with each command? | -- | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | -- | Go to Step 7 | Go to Step 6 | |
6 | Test the control circuit of the relay for a short to voltage or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the relay for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Inspect for faulty connections at the relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Inspect for faulty connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Repair the feed circuit of the relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the A/C clutch relay. Refer to Compressor Relay Replacement in HVAC. Did you complete the replacement? | -- | Go to Step 13 | -- |
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 13 | -- | |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
