P0622

P0622-GENERATOR FIELD CONTROL CIRCUIT







- When Monitored:
With the ignition on. Engine running.

- Set Condition:
When the Powertrain Control Module (PCM) tries to regulate the generator field with no result during monitoring. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Ignition on, engine not running.
2. With a scan tool, read the DTCs.

Is the DTC active at this time?

Yes

- Go To 2

No

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

2. GENERATOR OPERATION




1. Turn the ignition off.
2. Disconnect the Generator Field harness connector.
3. Using a 12-volt test light, jump it across the Generator Field harness connector.
4. Ignition on, engine not running.
5. 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 3

3. (K20) GEN FIELD CIRCUIT SHORTED BATTERY VOLTAGE




1. Turn the ignition off.
2. Disconnect the PCM harness connectors.
3. Ignition on, engine not running.
4. Measure the voltage on the (K20) Gen Field Control circuit in the Generator Field harness connector.

Is the voltage above 1.0 volt?

Yes

- Repair the short to battery voltage in the (K20) Gen Field Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (K20) GEN FIELD CIRCUIT OPEN




1. Turn the ignition off.

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.

2. Measure the resistance of the (K20) Gen Field Control circuit from the Generator Field harness connector to appropriate terminal the PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the open in the (K20) Gen Field Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. (K20) GEN FIELD CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K20) Gen Field Control circuit in the Generator Field harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (K20) Gen Field Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. GENERATOR CASE GROUND HIGH RESISTANCE

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 may result in possible serious or fatal injury.

1. Ignition on, engine not running.
2. Start the engine.
3. Allow the engine to reach normal operating temperature.

NOTE: Make sure all wires are clear of the engines moving parts.

4. Measure the voltage between the Generator case and Battery ground post.

Is the voltage above 0.1 of a volt?

Yes

- Repair excessive resistance in the Generator Ground between the Generator Case and Battery ground side.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 7

7. POWERTRAIN CONTROL MODULE (PCM)

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

1. 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. Powertrain Verification Test.

No

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