P0622
P0622 - Generator Field Control Circuit
For wiring diagrams, refer to.
• When Monitored: With the engine running, battery voltage greater than 10.4 volts, and the generator control active.
• Set Condition: The PCM detects an open or shorted condition in the generator control circuit.
• 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
• Turn the ignition ON.
• With the scan tool, clear DTCs in the PCM.
• Start the engine and allow it to reach operating temperature.
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.
• Increase engine speed by pressing the accelerator pedal. Do not exceed 3500 rpm.
• With the scan tool, select view DTCs.
Is the status active for this DTC?
Yes
• Go to Test Step 2 => [ Test
Step 2 - Generator Field Control Circuit Shorted to Ground ]
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 Field Control Circuit Shorted to Ground
• Turn the ignition OFF.
• Disconnect the generator connector.
• Disconnect the C2 PCM connector.
• Measure the resistance between ground and the generator field control circuit in the generator harness connector.
Is the resistance more than 100 ohms?
Yes
• Go to Test Step 3 => [ Test
Step 3 - Generator Field Control Circuit Open or High Resistance ]
No
• Repair the short to ground in the generator field control circuit.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 3 - Generator Field Control Circuit Open or High Resistance
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 generator field control circuit between the generator harness connector and the appropriate terminal of special tool #8815.
Is the resistance less than 5.0 ohms?
Yes
• Go to Test Step 4 => [ Test
Step 4 - Generator ]
No
• Repair the open or high resistance in the generator field control circuit.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
Test Step 4 - Generator
• Connect the C2 PCM connector.
• Turn the ignition ON.
• With the scan tool, actuate the alternator field control state.
• Using a test lamp connected to ground, check the generator field control circuit in the generator harness connector.
• The test lamp should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery.
Is the test lamp illuminated during the actuation?
Yes
• Replace the generator.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 5 => [ Test
Step 5 - PCM ]
Test Step 5 - 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