P063A-GENERATOR VOLTAGE SENSE CIRCUIT

For a complete wiring diagram Refer to Section 8W

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.

Possible Causes

INTERMITTENT DTC

(A804) GEN SENSE CIRCUIT SHORTED TO VOLTAGE

(A804) GEN SENSE CIRCUIT SHORTED TO GROUND

(A804) GEN SENSE CIRCUIT OPEN OR HIGH RESISTANCE

GENERATOR

POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

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. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

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. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Go to 4

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

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

Repair the (A804) Gen Sense circuit for an open circuit or high resistance.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

5. GENERATOR

Connect the Generator connector.
Connect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
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 6

Replace the Generator in accordance with the Service Information.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

6. 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.
Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.

Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).

Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).