P0645
DTC P0645 A/C CLUTCH RELAY CONTROL CIRCUITComponent Location:
GENERAL DESCRIPTION
The A/C relay is activated if the A/C switch is ON while the blower is running and system operation is enabled the PCM. Power is then supplied to the A/C compressor electromagnetic clutch and A/C system is operated. The A/C compressor is switched out to prevent it running when full engine output is required or there is a risk of overheating.The PCM also inhibits compressor operation on starting to permit running conditions to stabilize
DTC DESCRIPTION
PCM sets DTC P0645 if the PCM detects that A/C relay control line is open or short to ground or battery line.
DTC Detecting Condition:
Specification:
Schematic Diagram:
MONITOR DTC STATUS
This is the inspection procedure to determine whether it is present DTC or memoried one by monitoring the current signal or by using the function of oscilloscope with Hi-scan pro.
1. Connect scantool to Data Link Connector(DLC).
2. Warm up the engine to normal operating temperature.
3. Monitor the "A/C Relay" parameter on the scantool.
NOTE: The data shown above is only for reference and there may be a little difference actually.
Service standard
4. Is parameter displayed within specifications?
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO: Go to "W/Harness Inspection" procedure.
TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of vehicle Repair" procedure.
NO: Go to "Power Circuit inspection" procedure.
POWER CIRCUIT INSPECTION
1. Check for open in harness
1. Ignition "OFF"
2. Disconnect A/C Relay.
3. Ignition "ON" & Engine "OFF"
4. Measure voltage between terminal 1 and 5 of A/C Relay harness connector and chassis ground.
Specification: approximately B+
5. Is measure voltage within Specification?
YES: Go to "Control circuit inspection" procedure.
NO:
- Open circuit or short circuit to chassis ground between A/C Relay harness connector and A/C FUSE 10 A
- Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
CONTROL CIRCUIT INSPECTION
1. Ignition "OFF"
2. Disconnect A/C Relay.
3. Ignition "ON" & Engine "OFF"
4. Measure voltage between terminal 3 of A/C Relay harness connector and chassis ground.
Specification approximately 3.7 V
5. Is measure voltage within Specification?
YES: Go to "Component Inspection" procedure.
NO:
- Check for open or Short to battery in control circuit.
- Check for open or Short to ground in control circuit
- Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
NOTE:
1. In case,when A/C Relay connector is disconnected,the voltage at terminal 3 is 12 V.
- Possible cause: Short to battery in control circuit
2. In case,when A/C Relay connector is disconnected,the voltage at terminal 3 is 0 V.
- Possible cause: Short to ground in control circuit
COMPONENT INSPECTION
1. Check A/C Relay
1. Ignition "OFF"
2. Disconnect A/C Relay.
3. Measure resistance between terminal 3 and 5 of A/C Relay connector(To sensor side)
Specification: approximately 70 - 120 Ohms
4. Is measure resistance within Specification?
YES: Substitute with a known-good PCM and check for proper operation. If the problem is corrected, replace PCM and then go to "Verification of Vehicle Repair" procedure.
NO: Substitute with a known-good A/C Relay heater and check for proper operation. If the problem is corrected, replace A/C Relay and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code (DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all rediness test have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.