P0622

DTC P0622 (Gasoline)

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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 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 ON and the engine is OFF, the ECM should detect a duty cycle near 0 percent. When the engine is running, the duty cycle should be between 5-99 percent.


Conditions for Running the DTC

* The engine is running.
* The battery voltage is 9.5-18 V.



Conditions for Setting the DTC

The GEN F-Terminal Signal is less than 5 percent for 30 seconds.


Action Taken When the DTC Sets

* The charge indicator turns ON.
* The driver information center (DIC) displays the SERVICE BATTERY CHARGING SYSTEM message.



Conditions for Clearing the DTC

* The DTC will pass when the condition for setting the DTC is no longer present.
* A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
* The charge indicator and DIC message will remain ON until the DTC passes or is cleared, even if the ignition is cycled.



Reference Information
Schematic Reference

Starting and Charging Schematics (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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (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 parameter should read 0%.
2. Engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read between 5 and 99%.



Circuit/System Testing

1. Verify that a test lamp illuminates between the B+ circuit 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 0%.

• If greater than the specified value, test the field duty cycle circuit terminal 2 X1 for a short to voltage. If the circuit tests normal, replace the ECM.

4. Connect a test lamp between the field duty cycle circuit terminal 2 X1 and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%.

• 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 theDiagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Generator Replacement (4.3L) (Generator Replacement)Generator Replacement (6.6L) (Generator Replacement)Generator Replacement (4.8L, 5.3L, 6.0L, and 6.2L) (Generator Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming.