P063A-GENERATOR VOLTAGE SENSE CIRCUIT

For a complete wiring diagram Refer to Section 8W.

When Monitored:
The engine running. The engine speed greater than 1157 RPM.
Set Condition:
The PCM recognizes the alternator output voltage is less than the Battery feed circuit voltage. One trip failure. The Generator light will illuminate. The fault will be checked again on the next key cycle.

EXCESSIVE RESISTANCE IN THE (A804) GENERATOR SENSE CIRCUIT

(A804) GENERATOR SENSE CIRCUIT SHORTED TO GROUND

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1. ACTIVE DTC

NOTE: Inspect the vehicle for aftermarket accessories that may exceed the Generator System output.

NOTE: The battery must be fully charged.

NOTE: The Generator belt tension and condition must be checked before continuing.

Ignition on, engine not running.
With a scan tool, select View DTCs.
Start the engine.
Allow the idle to stabilize.
With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

Go To 2

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

2. EXCESSIVE RESISTANCE IN THE (A804) GENERATOR SENSE CIRCUIT

Turn the ignition off.
Disconnect the Generator harness connector.
Disconnect the C1 PCM harness connector.

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 to perform diagnosis.

Measure the resistance of the (A804) Generator Sense circuit from the Generator harness connector to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

Go To 3

Repair the excessive resistance in the (A804) Generator Sense circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3. (A804) GENERATOR SENSE CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (A804) Generator Sense circuit at the Generator harness connector.

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (A804) Generator Sense circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 4

4. GENERATOR OPERATION

Connect the C1 PCM harness connector.
Using a 12-volt test light connected to ground, probe the (K125) Generator Field Control circuit in the Generator Field harness connector.
Ignition on, engine not running.

NOTE: The DTC needs to be cleared before actuating the Solenoid, if the DTC is not cleared, the Solenoid may not be allowed to actuate.

With a scan tool, actuate the Generator Field Driver.

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

Yes

Replace the Generator.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 5

5. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes

Repair as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)