P0643

P0643-HIGH VOLTAGE AT THE #2 SENSOR SUPPLY CIRCUIT





For complete wiring diagrams refer to Diagrams/Electrical.


- When Monitored:

With the key on.

- Set Condition:

Voltage detected on the #2 sensor supply circuit was above a calibrated value.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. FAN CLUTCH ASSEMBLY

Disconnect the Fan clutch harness connector.


NOTE: Check connectors - Clean/repair as necessary.

With the scan tool, read DTCs.

Did P0483 set?

Yes

- Replace the Fan clutch assembly.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 2

2. (K668) 5-VOLT SHORTED TO VOLTAGE





Disconnect the ECM harness connectors.

Disconnect the Fan harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the voltage between the fan speed sensor (K668) 5-volt supply circuit and battery negative.

Is the voltage greater than 1 volt?

Yes

- Repair the (K668) 5-volt supply shorted to voltage.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3

3. ECM





Turn the ignition off.

Reconnect the ECM harness connectors.

Turn the ignition on.

Measure the voltage between the (K668) 5-volt supply circuit in the sensor harness connector and battery negative.

Is the voltage greater than 6 volts?

Yes

- Replace the ECM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition