Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0622: Generator F-Terminal CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
B+ | B1492, P0622* | B1492, P0622* | -- | -- |
Field Duty Cycle Signal | B1492, P0622* | B1492, P0622* | P0622* | -- |
Turn On Signal | B1487 | -- | B1488 | -- |
* 3.7L (LLR) engine only | ||||
Typical Scan Tool Data
Circuit | Short to ground | Open | Short to voltage |
|---|---|---|---|
Operating Conditions: Engine Running Parameter Normal Range: 5% to 99% | |||
B+ | 0% | 0% | -- |
Field Duty Cycle Signal | 0% | 0% | 99% |
Circuit 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 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 ignition 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 5-100 percent.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set. |
Conditions for Setting the DTC
| • | Ignition ON engine OFF, the ECM detects a PWM signal greater than 65 percent for 5 seconds |
| • | Engine running, the ECM detects a PWM signal less than 5 percent for 15 seconds. |
Action Taken When the DTC Sets
DTC P0622 is a type C DTC.
Conditions for Clearing the DTC
DTC P0622 is a type C DTC.
Reference Information
Schematic Reference
Starting and Charging Schematics
Connector End View Reference
Description and Operation
Charging System Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, engine OFF, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read 0%.
- Engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read between 5 and 99%.
Circuit/System Testing
- Verify that a test lamp illuminates between the B+ circuit terminal A X2 and ground.
- Ignition OFF, disconnect the X1 harness connectors at the generator and GBCM.
- Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0%.
- Connect a test lamp between the field duty cycle signal circuit terminal 2 X1 of the generator harness and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%.
- Reconnect the GBCM harness connector. Disconnect the test lamp.
- Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0%.
- Connect a test lamp between the field duty cycle circuit terminal 2 X1 of the generator harness and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%.
- If all circuits test normal, test or replace the generator.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If greater than the specified value, test the field duty cycle signal circuit terminal 2 X1 for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | 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. |
| ⇒ | If greater than the specified value, replace the GBCM. |
| ⇒ | If less than the specified range, replace the GBCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming. |
