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 |
|---|---|---|---|---|
B+ | P0622 | P0622 | -- | -- |
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. The generator field duty cycle signal circuit connects to high side of the field windings in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field windings 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 status of the generator field duty cycle signal circuit. When the Ignition is in the RUN position and the engine is OFF, the ECM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5-95 percent.
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
| • | DTC P0621 is not set. |
| • | 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
The instrument panel cluster (IPC) illuminates the charge indicator.
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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
With the scan tool installed, ignition ON and the engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read between 5 and 95 percent.
Circuit/System Testing
- Verify that a test lamp illuminates between the generator output B+ circuit terminal 1 X2 and ground.
- Ignition OFF, disconnect the harness connector X1 at the generator.
- Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter displays less than 5 percent.
- Install a 3A fused jumper wire between B+ and the signal circuit.
- Verify the scan tool ECM GEN-F Terminal Signal parameter displays greater than 95 percent.
- If the circuit tests normal replace the generator.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If greater than the specified range, test the signal circuit terminal 2 X1 for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
