P0626

DTC P0626

Diagnostic Instructions
^ Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure. Diagnostic System Check - Vehicle Diagnostic Information
^ Review [Strategy Based Diagnosis] for an overview of the diagnostic approach. Strategy Based Diagnosis
^ [Diagnostic Procedure Instructions - Vehicle Diagnostic Information] provides an overview of each diagnostic category. Diagnostic Procedure Instructions - Vehicle Diagnostic Information

DTC Descriptor
DTC P0626 Generator F-Terminal Circuit High Voltage

Diagnostic Fault Information






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
^ The engine is not running.
^ The ignition is in the ON position.

Conditions for Setting the DTC
The ECM detects a pulse width modulated (PWM) signal greater than 65 percent for at least 15 seconds.

Action Taken When the DTC Sets
DTC P0626 is a C type DTC.

Conditions for Clearing the DTC
DTC P0626 is a C type DTC.

Circuit/System Verification
Ignition ON, engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The GEN-F Terminal Signal parameter should read between 5-95 percent.

Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the generator.
2. Ignition ON, engine OFF, observe the scan tool ECM GEN-F Terminal Signal parameter. It should display less than 10 percent.
^ If the GEN-F Terminal Signal parameter was not affected by the disconnected generator harness, test the GEN-F Terminal Signal circuit terminal 2 for a short to voltage.If the circuit tests normal, replace the ECM.
^ If the circuit tested normal and the ECM parameter changed from above 65 percent to less than 10 percent, replace the generator.

Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure. Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [Generator Replacement]