GPEC

P063A-GENERATOR VOLTAGE SENSE CIRCUIT





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the engine running and battery voltage greater than 10.4 volts.

- Set Condition:
The PCM detects no change when attempting to regulate the generator output.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking For An Intermittent DTC

2. (A804) GEN SENSE CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Disconnect the Generator connector.
Disconnect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
Measure the voltage of the (A804) Gen Sense circuit in the Generator harness connector.
Is there any voltage present?

Yes

- Repair the (A804) Gen Sense circuit for a short to voltage.
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.

No

- Go to 3

3. (A804) GEN SENSE CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Measure the resistance between ground and the (A804) Gen Sense circuit in the Generator harness connector.
Is the resistance below 100 ohms?

Yes

- Repair the (A804) Gen Sense circuit for a short to ground.
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.

No

- Go to 4

4. (A804) GEN SENSE CIRCUIT OPEN OR HIGH RESISTANCE




NOTE: When checking circuits at the Powertrain Control Module (PCM), be careful not to damage or distort the connector terminals. Improper measurement technique could result in poor pin to terminal contact.

Measure the resistance of the (A804) Gen Sense circuit between the Generator harness connector and the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go to 5

No

- Repair the (A804) Gen Sense circuit for an open circuit or high resistance.
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.

5. GENERATOR FIELD CONTROL ACTUATION




WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Connect the Generator connector.
Connect the Powertrain Control Module (PCM) connector.
Turn the ignition on.

NOTE: When checking circuits at the Powertrain Control Module (PCM), be careful not to damage or distort the connector terminals. Improper measurement technique could result in poor pin to terminal contact.

While backprobing, measure the voltage of the (K20) Gen Field Control circuit in the Powertrain Control Module (PCM) harness connector.
Start the engine.
With the scan tool, perform the Generator Full Field test.
Monitor the voltage of the (K20) Gen Field Control circuit with the Generator Full Field test actuated.

NOTE: The voltage should increase more than 1 volt.

Does the voltage increase by at least 1 volt with the Generator Full Field Test on?

Yes

- Go to 7

No

- Go to 6

6. GENERATOR
Turn the ignition off.
Inspect the wiring and connectors between the Generator and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related connectors.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.

No

- Replace the Generator.
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.

7. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Generator and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test Ver. 1Powertrain Verification Test.