P063A

P063A - Generator Voltage Sense Circuit






For wiring diagrams, refer to.

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

• Set Condition: The PCM detects no change in the sensed Generator voltage when attempting to regulate the generator output.






• Always perform the pre-diagnostic troubleshooting procedure before proceeding. Refer to => Non-DTC Based Diagnostics. Pre-Diagnostic Troubleshooting Procedure

Test Step 1 - DTC is Active

• Start the engine and allow it reach operating temperature.

• With the scan tool, select view DTCs.

Is the status active for this DTC?

Yes

• Go to Test Step 2 => [ Test
Step 2 - Generator Sense Circuit Shorted to Voltage ]

No

• Refer to the checking for an intermittent DTC diagnostic procedure. Refer to => Non-DTC Based Diagnostics. Checking for an Intermittent DTC

Test Step 2 - Generator Sense Circuit Shorted to Voltage






• Turn the ignition OFF.

• Disconnect the generator connector.

• Disconnect the PCM connector.

• Turn the ignition ON.

• Measure the voltage of the generator sense circuit in the generator harness connector.

Is there any voltage present?

Yes

• Repair the generator sense circuit for a short to voltage.

• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test

No

• Go to Test Step 3 => [ Test
Step 3 - Generator Sense Circuit Shorted to Ground ]

Test Step 3 - Generator Sense Circuit Shorted to Ground






• Turn the ignition OFF.

• Measure the resistance between ground and the generator sense circuit in the generator harness connector.

Is the resistance less than 100 ohms?

Yes

• Repair the generator sense circuit for a short to ground.

• Perform the PCM Verification Test.Refer to => Non-DTC
Based Diagnostics. PCM Verification Test

No

• Go to Test Step 4 => [ Test
Step 4 - Generator Sense Circuit Open or High Resistance ]

No

• Repair the generator sense circuit for an open or high resistance.

• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test

Test Step 5 - Generator


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 PCM connector.

• Turn the ignition ON.


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.

• While backprobing, measure the voltage of the generator sense circuit in the appropriate terminal of special tool #8815-1.

• Start the engine.

• With the scan tool, perform the generator full field test.

• Monitor the voltage of the generator sense circuit with the generator full field test actuated.

• 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 Test Step 6 => [ Test
Step 6 - PCM ]

No

• Replace the generator.

• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test

Test Step 6 - PCM

• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the generator and the 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. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test

No

• Replace and program the PCM.

• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics PCM Verification Test