P0622

DTC P0622 (Diesel)

Circuit Description

The engine control module (ECM) uses the generator field duty cycle signal circuit to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding ON and OFF. The ECM uses the PWM signal input to determine the generator load on the engine. This allows the ECM to adjust the idle speed to compensate for high electrical loads.

Conditions for Running the DTC

IGN ON Test
- No generator, CKP sensors, or CMP sensor DTCs are set.
- The key is in the RUN position.
- The engine is not running.

Run Test
- No generator, CKP sensors, or CMP sensor DTCs are set.
- The engine is less than 3,000 RPM.

Conditions for Setting the DTC

- During the ignition ON test, the ECM detects a PWM signal is out of range.
- During the RUN test, the ECM detects a PWM signal less then 5 percent for more than 6 seconds.

Action Taken When the DTC Sets

- The ECM will store the conditions present when the DTC set as Fail Records data only.
- The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC

- The Conditions for Setting the DTC are no longer present.
- A history DTC will clear after 40 malfunction free ignition cycles.
- The engine control module (ECM) receives the clear code command from the scan tool.