P0643

P0643

Component Location:

General Description
The 5 V reference line is monitored for malfunctions that could result in improper sensor operation.

DTC Description
When PCM detects that the power for sensors (5 V) is over 5.75 V during 3 sec or more, PCM sets DTC P0643.

DTC Detecting Condition:

Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC).
2. Warm up the engine to normal operating temperature.
3. Monitor the sensors which use 5 V for power (ex. TPS, ECTS, IATS, FTPS, etc) on the scantool.






4. Are the parameters displayed correctly?

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 "Inspection & Repair" procedure.

Terminal and 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 Supply Circuit Inspection
1. Check voltage
1. IG "OFF".
2. Disconnect IATS, ECTS, TPS and FTPS harness connector.
3. IG "ON".
4. Measure the voltage between terminal 3 of IATS harness connector and ground.
Measure the voltage between terminal 1 of ECTS harness connector and ground.
Measure the voltage between terminal 2 of TPS harness connector and ground.
Measure the voltage between terminal 3 of FTPS harness connector and ground.

Specification : approx. 5 V











5. Is the measured voltage within specification?

YES - 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 "Check Short to power" procedure.

2. Check Short to power
1. IG "OFF".
2. Disconnect IATS, ECTS, TPS, FTPS and ECM harness connector.
3. Measure the resistance between terminal 3 and 2 of IATS harness connector.
Measure the resistance between terminal 1 and 2 of ECTS harness connector.
Measure the resistance between terminal 2 of TPS harness connector and Battery (+).
Measure the resistance between terminal 3 of FTPS harness connector and Battery (+).

Specification : Infinite






4. Is the resistance within specification?

YES - Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure.

NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others

NO - Repair Short to battery in power circuit 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. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present?

YES - Go to the applicable troubleshooting procedure.

NO - System is performing to specification at this time.