P0647
DTC P0647 A/C CLUTCH RELAY CONTROL CIRCUIT HIGHComponent Location:
GENERAL DESCRIPTION
The A/C clutch relay is activated if the A/C switch is operated while the blower is running and system operation is enabled by the ECM. When A/C is requested, the Engine Control Module (ECM) provides a ground path to the A/C clutch relay control circuit. When the relay circuit is grounded, the A/C clutch relay is energized. The ECM delays grounding the relay circuit for a short time, so the ECM can adjust the engine idle speed for the additional load. The ECM will temporarily de-energized the A/C clutch relay for one or more of the following conditions:
- Full acceleration when the throttle is at WOT. (Wide Open Throttle)
- Risk of overheating: Engine coolant temp. exceeds threshold value
- A/C system pressure exceeds threshold value
- Engine starting
DTC DESCRIPTION
ECM sets DTC P0647 if the ECM detects signal voltage lower than the possible range of a properly operating A/C clutch relay.
DTC Detecting Condition:
Specification:
Schematic Diagram:
MONITOR DTC STATUS
NOTE: If any codes relating to A/C Refrigerant Pressure Sensor are present, do ALL REPAIRS associated with those codes before proceeding with this troubleshooting tree.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Read "DTC Status" parameter.
5. Is parameter displayed "History (Not Present) fault"?
NOTE:
- History (Not Present) fault : DTC occurred but has been cleared.
- Present fault : DTC is occurring at present time
YES - Fault is intermittent, caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO - Go to next step as below
COMPONENT INSPECTION
1. With Ignition OFF, remove the A/C comp. relay
2. Measure resistance between terminals 85 and 86 of the A/C comp. relay (Component side)
Specification : Approx. 70 - 120 Ohms at 20 °C(68 °F)
3. Apply 12 V and a ground to 85 and 86 terminals of the A/C comp. relay (Components side).
4. Check if the main relay works well when it is energized. (If the A/C comp. relay works normally, a clicking sound can be heard.)
5. Does the A/C comp. relay operate normally?
YES - Go to next step as below
NO - Check A/C comp. relay for contamination, deterioration, or damage. Substitute with a known-good A/C comp. relay and check for proper operation. If the problem is corrected, replace A/C comp. relay and then go to "Verification of Vehicle Repair" procedure
CONTROL CIRCUIT INSPECTION
1. Measure the voltage between terminal 86 of the A/C comp. relay harness connector and chassis ground.
Specification : 4 - 5 V
2. Is voltage within the specification?
YES - Go to next step as below
NO - Check for open or short in control circuit. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness(es) 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 - Thoroughly check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and 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. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History (Not Present) fault"?
YES - System performing to specification at this time. Clear the DTC
NO - Go to the applicable troubleshooting procedure.