• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
B+ | P0622 | P0622 | -- | -- |
Field Duty Cycle Signal | P0622 | P0622 | P0622 | -- |
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% |
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 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 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 percent and 100 percent. The ECM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the ECM detects an out of range PWM signal, DTC P0622 will set.
• | The ignition is ON. |
• | No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set. |
• | 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. |
DTC P0622 is a type C DTC.
DTC P0622 is a type C DTC.
Starting and Charging Schematics
Charging System Description and Operation
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming. |