P0642
DTC P0642 SENSOR REFERENCE VOLTAGE "A" CIRCUIT LOWComponent Location:
GENERAL DESCRIPTION
The ECM provides a 5 volt reference voltage to the Acceleration Position Sensor2 (APS 2), A/C pressure sensor and power steering sensor. The ECM monitors reference voltage deviation from the power supply circuit of the sensors
DTC DESCRIPTION
ECM sets DTC P0642 if the ECM detects reference voltage lower than threshold value.
DTC Detecting Condition:
Schematic Diagram:
MONITOR DTC STATUS
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 the ECM's connector, which was repaired but 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
POWER CIRCUIT INSPECTION
1. Ignition "OFF".
2. Disconnect APS 2 harness connector.
3. Ignition "ON" & Engine "OFF".
4. Measure voltage between terminal 1 of the APS 2 harness connector and chassis ground.
Specification : Approx. 5 V
5. Is voltage within the specification?
YES - Go to next step as below
NO - 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 - Check ECM for contamination, deterioration, or damage. Substitute with a known-good ECM and check for proper operation. If the problem is corrected, replace ECM and then go to "Verification of Vehicle Repair" procedure.
NOTE: It is necessary to perform the TPS adaptation procedure with Scan tool when the throttle body assembly or ECM is replaced.
- TPS adaptation procedure
1. Erase previous TPS adaptation value using Scan tool.
2. Ignition "OFF" and then "ON" without cranking. Wait for 10 seconds under enable conditions
- Enable conditions : Battery 10 V & Intake Air Temp. 5.3 °C(41.5 °F) & 5.3 °C(41.5 °F) Engine Coolant Temp. 99.8 °C(211.6 °F)
3. After TPS adaptation, the system normality should be confirmed by reading out "FMY" on the Scan Tool.
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.