P0643

P0643-SENSOR REFERENCE VOLTAGE 1 CIRCUIT HIGH





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

This sensor supply circuit provides a 5-Volt supply to the Crankshaft Position Sensor. A MIL lamp will be lit immediately after this diagnostic runs and fails. The MIL lamp will turn off once the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
With the key on.

- Set Condition:
Voltage detected on the 5-Volt Supply circuit was above a calibrated value.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. CHECK THE (K824) 5-VOLT CIRCUIT FOR A SHORT TO VOLTAGE




1. Disconnect the Crankshaft Position Sensor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

2. Measure the voltage on the (K824) 5-Volt Supply circuit at the Crankshaft Position Sensor harness connector.

Is the voltage greater than 5.1 Volts?

Yes

- Go To 3

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

3. CHECK THE (K824) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
1. Disconnect the PCM C1 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

2. Measure the resistance between the (K824) 5-Volt Supply circuit and all other circuits in the PCM C1 connector.

Is the resistance below 10k Ohms between the (K824) 5-Volt Supply circuit and any of the circuits?

Yes

- Repair the short to the circuit that measured below 10k Ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.