P063A

P063A-GENERATOR VOLTAGE SENSE CIRCUIT







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

- Set Condition:
The Powertrain Control Module (PCM) detects no change 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 status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. (A803) GEN SENSE CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Generator connector.
3. Disconnect the Powertrain Control Module (PCM) harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (A803) Gen Sense circuit in the Generator harness connector.

Is there any voltage present?

Yes

- Repair the (A803) Gen Sense circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (A803) GEN SENSE CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Measure the resistance between ground and the (A803) Gen Sense circuit in the Generator harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the (A803) Gen Sense circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (A803) GEN 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 (A803) Gen Sense circuit between the Generator harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the (A803) Gen Sense circuit for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. GENERATOR
1. Connect the Powertrain Control Module (PCM) connector.
2. Ignition on, engine not running.
3. Using a 12-volt test light, jump it across the Generator Field harness connector.
4. With the scan tool, actuate the Alternator Field Duty Cycle.

Does the test light illuminate brightly and flash on and off?

Yes

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

No

- Go To 6

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. Look for broken, bent, pushed out or corroded terminals.
4. Search for any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

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