P0642

P0642-LOW 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 is below 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 GROUND





Turn the ignition off.

Disconnect the ECM harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the (K668) #2 5-volt supply (fan speed sensor power) circuit in the sensor harness connector and battery negative.

Is the resistance greater than 100k Ohms?

Yes

- Go To 3

No

- Repair the #2 (K668) 5-volt supply shorted to ground.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. (K668) 5-VOLT SUPPLY SHORTED TO ANOTHER CIRCUIT





Measure the resistance between the sensor (K668) #2 5-volt supply (fan speed sensor power) circuit in the ECM harness connector to all other circuits in the ECM harness connectors

Is the resistance greater than 100k Ohms?

Yes

- Go To 4

No

- Repair the 5-volt supply shorted to another circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. FAN DTC

Reconnect the ECM harness connectors.

Reconnect the disconnected Fan harness connector.

Turn the ignition on.

With the scan tool, read DTCs.

Is DTC P0483 set?

Yes

- Repair the Fan DTC.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 5

5. ECM





Turn the ignition off.

Disconnect the Fan harness connector.

Turn the ignition on.

Measure the voltage between the sensor (K668) #2 5-volt supply (fan speed sensor power) circuit at the fan clutch harness connector and the fan speed sensor ground.

Is the voltage between 4.5 and 5.5 volts?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

No

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