Mazda Factory OBD-II DTC P0645 Code Diagnostic Procedure

P0645 A/C clutch relay circuit malfunction
DETECTION CONDITION
•  The PCM monitors the input voltage from the A/C clutch relay signal. If the voltages at PCM deviates from the threshold, the PCM terminal 303 determines that the there is a A/C clutch relay range/performance malfunction.
POSSIBLE CAUSE
•  A/C clutch relay malfunction
•  Connector or terminal malfunction
•  Open circuit in the wiring harness between fuse and A/C clutch relay terminal A
•  Open circuit in the wiring harness between A/C clutch relay terminal E and PCM terminal 303
•  PCM malfunction

Diagnostic procedure

STEP INSPECTION ACTION
1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
•  Has the FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED REPAIR INFORMATION AVAILABILITY
•  Verify related service repair information availability.
•  Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY CURRENT SIGNAL STATUS: IS CONCERN INTERMITTENT OR CONSTANT?
•  Connect the M-MDS to the DLC-2.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Run the vehicle under the FREEZE FRAME DATA stored condition.
•  Is the same DTC present?
Yes
Go to the next step.
No
Intermittent concern exists.
Perform the “INTERMITTENT CONCERNS TROUBLESHOOTING”.
4
INSPECT A/C CLUTCH RELAY CONNECTOR FOR POOR CONNECTION
•  Turn the engine switch to the ON position.
•  Inspect for poor connection (such as damaged/pulled-out terminals, corrosion).
•  Is there any malfunction?
Yes
Go to the next step.
No
Repair or replace the terminal, then go to Step 9.
5
INSPECT A/C CLUTCH RELAY POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT
•  Turn the engine switch to the ON position.
•  Measure the voltage at A/C clutch relay terminal A.
•  Is the voltage B+?
Yes
Go to the next step.
No
Repair or replace the wiring harness for an open circuit, then go to Step 9.
6
INSPECT A/C CLUTCH RELAY
•  Inspect the A/C clutch relay.
•   Is there any malfunction?
Yes
Replace the A/C clutch relay, then go to Step 9.
No
Go to the next step.
7
INSPECT PCM CONNECTOR FOR POOR CONNECTION
•  Turn the engine switch off.
•  Inspect for poor connection (such as damaged/pulled-out terminals, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the terminal, then go to Step 9.
No
Go to the next step.
8
INSPECT A/C CLUTCH RELAY SIGNAL CIRCUIT FOR OPEN CIRCUIT
•  Turn the engine switch off.
•  Inspect for continuity between A/C clutch relay terminal E and PCM terminal 303.
•  Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness for an open circuit, then go to the next step.
9
VERIFY THAT DTC P0645 TROUBLESHOOTING IS COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Run the vehicle under the FREEZE FRAME DATA stored condition.
•  Is the same DTC present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
10
VERIFY AFTER REPAIR PROCEDURE
•  Perform the after repair procedure.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
DTC troubleshooting completed.
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