P0622
DTC P0622
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0622
- Generator F-Terminal Circuit
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The engine control module (ECM) uses the generator field duty cycle signal circuit, or F-terminal 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 signal 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 switch 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 5-99 percent.
Conditions for Running the DTC
* The engine is running.
* DTCs P0621, P2500, and P2501 are not set.
Conditions for Setting the DTC
The ECM detects that the field duty cycle signal is less than 5 percent for 30 seconds.
Action Taken When the DTC Sets
The charge indicator turns ON.
Conditions for Clearing the DTC
* The DTC passes when the field duty cycle signal is greater than 5 percent for 30 seconds.
* The EBCM clears a history DTC when the DTC does not fail in 100 consecutive drive cycles.
* The charge indicator turns OFF when the DTC passes.
Reference Information
Schematic Reference
Starting and Charging Schematics ()
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Charging System Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Programming and Relearning (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, engine OFF, observe the scan tool ECM GEN-F Terminal Signal parameter. The reading should be less than 5%.
2. Engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The reading should be greater than 5%.
Circuit/System Testing
1. Verify that a test lamp illuminates between the B+ circuit ring terminal 1 X2 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
2. Ignition OFF, disconnect the X1 harness connector at the generator.
3. Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is less than 5%.
• If greater than the specified range, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the ECM.
* Terminal 2 X1 (L61/LE5)
* Terminal C X1 (LNF)
4. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%.
* Terminal 2 X1 (L61/LE5)
* Terminal C X1 (LNF)
• If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
5. If all circuits test normal, test or replace the generator.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Generator Replacement (Service and Repair)
* Programming and Relearning (Programming and Relearning) for ECM replacement, setup, and programming.