Test Procedure
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- AV1 PRELIMINARY DIAGNOSIS DIAGNOSTIC TROUBLE CODE (DTC) P0645
- Carry out a visual inspection.
- Retrieve and record all DTCs.
- Clear all DTCs.
- Carry out the on-demand self-test.
- Is DTC P0645 present?
Yes No GO to AV2. Unable to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the concern. REPAIR as necessary. REFER to appropriate CLIMATE CONTROL SYSTEM article, for A/C system concerns. - AV2 DTC P0645
- Possible causes:
- A/C clutch relay control circuit short to voltage
- A/C clutch relay control circuit open
- A/C clutch relay control circuit short to ground
- A/C clutch relay circuit
- A/C clutch relay
- PCM
- Key ON, engine OFF.
- Access the PCM and monitor the ACCS PID.
- Cycle the A/C control switch off and on.
- Does the ACCS PID indicate ON with the A/C control switch ON and OFF with the A/C control switch OFF?
Yes No GO to AV3. REFER to appropriate CLIMATE CONTROL SYSTEM article, to continue diagnosis of the A/C system. - Possible causes:
- AV3 CHECK THE A/C CLUTCH RELAY COIL POWER CIRCUIT FOR VOLTAGE NOTE: Refer to appropriate SYSTEM WIRING DIAGRAMS article for the A/C clutch relay coil pin locations.
- Key in OFF position.
- A/CC Relay connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) A/CC Relay Connector, Harness Side ( - ) VPWR - Pin 2 Ground - Is the voltage greater than 10 V?
Yes No GO to AV4. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. - AV4 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT
- Connect a non-powered test lamp between:
( + ) A/CC Relay Connector, Harness Side ( - ) A/CC Relay Connector, Harness Side A/CC PWR - Pin 5 A/CCR - Pin 1 - Key ON, engine running.
- Cycle the A/C control switch off and on.
- Is the test lamp illuminated with the A/C control switch on and is the test lamp off with the A/C control switch off?
Yes No REFER to appropriate CLIMATE CONTROL SYSTEM article, to continue diagnosis of the A/C system. GO to AV5. - Connect a non-powered test lamp between:
- AV5 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
- Key in OFF position.
- PCM connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) PCM Connector, Harness Side ( - ) A/CCR - Pin B2 Ground - Is the voltage less than 0.2 V?
Yes No GO to AV6. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. - AV6 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
- Key in OFF position.
- Measure the resistance between:
( + ) PCM Connector, Harness Side ( - ) A/CCR - Pin B2 Ground - Is the resistance greater than 10K ohms?
Yes No GO to AV7. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. - AV7 CHECK THE A/C CLUTCH RELAY CONTROL CIRCUIT FOR AN OPEN
- Measure the resistance between:
( + ) PCM Connector, Harness Side ( - ) A/CC Relay Connector, Harness Side A/CCR - Pin B2 A/CCR - Pin 1 - Is the resistance less than 5 ohms?
Yes No GO to AV8. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. - Measure the resistance between:
- AV8 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Visually inspect for:
- pushed out pins
- corrosion
- Connect all the PCM connectors and make sure they seat correctly.
- Carry out the PCM self-test and verify the concern is still present.
- Is the concern still present?
Yes No INSTALL a new PCM. REFER toFLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.