Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0622: Generator F-Terminal CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Generator Field Duty Cycle Signal | P0622 | P0622 | P0622 | P0622 |
Circuit/System Description
The engine control module (ECM) uses the generator field duty cycle signal circuit to monitor the duty cycle of the generator and fault indication. 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.
The ECM monitors the state of the generator field duty cycle signal circuit. When the engine is running, the ECM should detect a duty cycle that varies up to 100 percent. The ECM monitors the PWM signal using a Ignition ON test and a RUN test. During the tests, if the ECM detects an out of range PWM signal, a DTC will set.
Conditions for Running the DTC
| • | No generator, crankshaft position (CKP) sensor, or camshaft (CMP) sensor DTCs are set. |
| • | Ignition ON engine OFF, for the Ignition ON test. |
| • | Engine running, engine speed less than 3,000 RPM for the RUN test. |
Conditions for Setting the DTC
| • | Ignition ON engine OFF, the ECM detects a PWM signal greater than 65 percent for 5 seconds. |
| • | Engine running, the ECM detects a PWM signal less than 5 percent for 15 seconds. |
Action Taken When the DTC Sets
DTC P0622 is a C type DTC.
Conditions for Clearing the DTC
DTC P0622 is a C type DTC.
Reference Information
Schematic Reference
Starting and Charging Schematics
Connector End View Reference
Description and Operation
Charging System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the generator.
- Ignition ON, test the generator field duty cycle circuit X1 terminal C for a short to ground or an open/high resistance or a short to voltage.
| ⇒ | If the circuit tests normal, replace the generator. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
