P0622

DTC P0622

Diagnostic Instructions
^ Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure.
^ 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 P0622 Generator F-Terminal Circuit

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 key 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
^ The vehicle speed is above 8 km/h (5 mph).
^ The system voltage is between 9.5 18 volts.

Conditions for Setting the DTC
^ The ECM detects an out of range PWM signal during the KEY ON test.
^ The ECM detects a PWM signal greater than 65 percent for at least 5 seconds
^ The ECM detects a PWM signal less than 5 percent for at least 15 seconds during the RUN test.

Action Taken When the DTC Sets
^ The ECM will command the charge indicator and or warning message to be illuminated on the instrument panel cluster (IPC) and the driver information center (DIC), if equipped.
^ The ECM will not illuminate the malfunction indicator lamp (MIL).
^ The ECM will store conditions, which were present when the DTC set as Failure Records data only.

Conditions for Clearing the DTC
^ The ECM will command the message OFF after one trip in which the diagnostic test has been run and passed.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

Reference Information

Schematic Reference
[Starting and Charging Schematics]

Connector End View Reference
[Engine Electrical Connector End Views]

Description and Operation
[Charging System Description and Operation]

Electrical Information Reference
^ [Circuit Testing]
^ [Connector Repairs]
^ [Testing for Intermittent Conditions and Poor Connections]
^ [Wiring Repairs]

Scan Tool Reference
^ [Scan Tool Data List - Engine Electrical]
^ [Scan Tool Data Definitions - Engine Controls - 3.6L (LY7)]

Circuit/System Verification
Engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The 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, connect a test lamp to battery positive voltage and repeatedly probe the generator field duty cycle circuit, harness side while monitoring the GEN-F Terminal Signal Parameter in the ECM data list. It should change from 0 percent to above 95 percent.
^ If the parameter was not affected by the test lamp, test the signal circuit for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

3. If the circuit tests normal during the Ignition ON / RUN tests, and the ECM parameter changed from 0 percent to above 95 percent, replace the generator.

Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure.
^ [Control Module References] for ECM replacement, setup, and programming Programming and Relearning
^ [Generator Replacement]