Circuit Description
The PCM activates the A/C clutch relay when the PCM detects an A/C request signal. When the PCM activates the relay, voltage should be present at both the A/C compressor clutch and the A/C clutch status circuit at the PCM. The PCM monitors the A/C status circuit for voltage after the clutch is enabled. If the PCM does not detect a voltage this DTC sets.
Conditions for Running the DTC
The A/C is requested
Conditions for Setting the DTC
The PCM commands the A/C ON and the PCM detects no voltage on the A/C clutch status line for more than 5 seconds.
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The PCM disables the A/C. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A last test failed, or the current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL/DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM\TAC module connector surfaces before
servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets
when diagnosing/replacing the modules. Ensure that the gaskets are installed
correctly. The gaskets prevent contaminate intrusion into the PCM\TAC
modules. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | The following may cause an intermittent: |
| - | Poor connections; Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | For an intermittent condition, refer to Symptoms . |
A/C Clutch Relay Underhood Electrical Center Terminal Identification | |||
|---|---|---|---|
Front of Vehicle | |||
Left Side of Vehicle | Ignition | Load | Right Side of Vehicle |
Ignition | Control | ||
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the operation of the A/C compressor clutch. The PCM disables the A/C compressor clutch when this DTC is set.
-
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help 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 you observed. This will isolate when the DTC failed.
-
This step verifies whether the ignition voltage is available at the relay.
-
This step determines if the A/C relay is at fault or the A/C status circuit is at fault. If the A/C clutch engages, this indicates that the A/C Status circuit is OK.
-
If the A/C Status is displayed as OFF, this indicates the A/C status circuit is open between the splice and the PCM. If the A/C Status is displayed as ON, this indicates a faulty connection at the A/C compressor relay or a faulty relay.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
|
Important: Diagnose DTC P0645 first if it is set.
Does the A/C clutch operate properly? | 5 minutes | |||
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | ||
Does the test lamp illuminate? | -- | |||
Jumper the ignition feed circuit to the A/C clutch status circuit (load) at the underhood electrical center using a fused jumper wire. Refer to Diagnostic Aids for terminal identification. Does the A/C clutch engage? | -- | |||
Monitor the A/C Status display on the Engine 1 Data List using the scan tool with the fused jumper still installed. Does the scan tool indicate the A/C Status as ON? | -- | |||
7 | Repair the faulty A/C clutch relay connection or replace the faulty A/C clutch relay. Is the action complete? | -- | -- | |
8 | Repair the open A/C clutch status circuit from the splice to the PCM. Refer to Wiring Repairs in Wiring Systems. Did you find and repair the condition? | -- | ||
9 | Repair the open ignition feed circuit to A/C clutch relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
10 | Repair the open in A/C status circuit from A/C clutch relay to splice. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
11 |
Did you find and correct the condition? | -- | ||
12 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Replace the PCM. Is the action complete? | -- | -- | |
13 |
Does the scan tool indicate that this failed? | -- | ||
14 | Select the Capture Info option and the Review Info option using the scan tool. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
