2010 Cadillac Truck SRX FWD V6-3.0L Page 1617
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
* 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 that is greater than 65 percent for 5 seconds.
* Engine running, the ECM detects a PWM signal that is 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 (See: Starting and Charging/Diagrams/Electrical Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)
Description and Operation
Charging System Description and Operation (See: Starting and Charging/Charging System/Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Engine running, observe the scan tool GEN-F Terminal Signal Circuit parameter. The GEN-F Terminal Signal Circuit parameter should display
between 5-99 percent.
Circuit/System Testing
1. Verify that a test lamp illuminates between the G13 generator B+ terminal A X2 and ground.
瀚慖f 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 G13 generator.
3. Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter displays less than 5 percent.
