P063A

P063A-GENERATOR VOLTAGE SENSE CIRCUIT







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

- Set Condition:
The PCM detects no change in the (A804) Generator Sense voltage when attempting to regulate the generator output.





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

1. DTC IS ACTIVE
1. Start the engine and allow it reach operating temperature.
2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking for an Intermittent DTC

2. (A804) GENERATOR SENSE CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the Generator connector.
3. Disconnect the C1 Powertrain Control Module (PCM) harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (A804) Generator Sense circuit in the Generator harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (A804) Generator Sense circuit.
- Perform the PCM Verification Test. PCM Verification Test

No

- Go to 3

3. (A804) GENERATOR SENSE CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Measure the resistance between ground and the (A804) Generator Sense circuit in the Generator harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (A804) Generator Sense circuit.
- Perform the PCM Verification Test. PCM Verification Test

No

- Go to 4

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





CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install PCM Pinout Box 8815 to perform diagnosis.

1. Measure the resistance of the (A804) Generator Sense circuit between the Generator harness connector and the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go to 5

No

- Repair the open or high resistance in the (A804) Generator Sense circuit.
- Perform the PCM Verification Test. PCM Verification Test

5. GENERATOR

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 may result in possible serious or fatal injury.

1. Connect the Generator connector.
2. Connect the C1 Powertrain Control Module (PCM) harness connector.
3. Turn the ignition on.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.

4. While backprobing, measure the voltage of the (A804) Generator Sense circuit in the appropriate terminal of special tool #8815-1.
5. Start the engine.
6. With the scan tool, perform the Generator Full Field test.
7. Monitor the voltage of the (A804) Generator Sense circuit with the Generator Full Field test actuated.

NOTE: The voltage should increase by more than 1 volt with the Generator fully fielded.

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

Yes

- Go to 6

No

- Replace the Generator.
- Perform the PCM Verification Test. PCM Verification Test

6. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Generator and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Verify that there is good pin to terminal contact in the Generator and Powertrain Control Module connectors.
4. Look for broken, bent, pushed out or corroded terminals.
5. Search for any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. PCM Verification Test

No

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