Refer to Engine Controls Schematic
Cell 20: A/C Compressor Controls
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. Unlike the Quad Driver Modules (QDMs) used in prior model years, 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 Setting the DTC
| • | The ignition is ON. |
| • | 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 the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM, turn the ignition ON and observe a digital multimeter connected between the A/C compressor control relay control circuit and ground at the PCM harness connector while moving connectors and wiring harnesses related to the A/C compressor control relay. A change in voltage will indicate the location of the malfunction. |
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does the DMM display a voltage near the specified value? | B+ | ||
3 |
Does the DMM display a current reading within the specified range? | 0.5-1.5 amps | ||
4 |
Does the test lamp flash? | -- | Go to Diagnostic Aids | |
5 |
Was a problem found? | -- | ||
6 |
Is the test lamp ON? | -- | ||
7 |
Was a problem found? | -- | ||
8 |
Was a problem found? | -- | ||
9 |
Is the test lamp ON? | -- | ||
10 |
Is the test lamp ON? | -- | ||
11 |
Is the test lamp ON? | -- | ||
12 |
Is the test lamp ON? | -- | ||
13 |
Is the test lamp ON? | -- | ||
14 | Locate and repair open in the B+ feed to cavity 87 in the ignition main relay. Refer to Wiring Repairs . Is action complete? | -- | -- | |
15 | Locate and repair open in the B+ feed to cavity 86 in the A/C relay. Refer to Wiring Repairs . Is action complete? | -- | -- | |
16 | Locate and repair the open in the B+ feed to cavity 86 in the ignition main relay. Refer to Wiring Repairs . Is action complete? | -- | -- | |
17 | Locate and repair open in the ignition main ground. Refer to Wiring Repairs . Is action complete? | -- | -- | |
18 | Locate and repair the short to voltage in the A/C relay control circuit. Refer to Wiring Repairs . Is action complete? | -- | -- | |
19 | Replace the A/C Relay. Is action complete? | -- | -- | |
20 | Replace the ignition main relay. Is action complete? | -- | -- | |
21 |
Important: Replacement PCM must be reprogrammed. Replace the PCM Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- | |
22 |
Does the scan tool indicate DTC P1546 failed this ignition? | -- | System OK |
