P0625
DTC P0625
Circuit 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. When the DTC sets, the ECM will send a class 2 serial data message to the instrument panel cluster (IPC) and driver information center (DIC) to illuminate the charge indicator or display a charging message.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0625 Generator F - Terminal Circuit Low Voltage
Conditions for Running the DTC
* No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
* The engine is less than 3,000 RPM.
* The generator has not been commanded OFF by the ECM or scan tool.
Conditions for Setting the DTC
The ECM detects a PWM signal less than 5 percent for at least 15 seconds.
Action Taken When the DTC Sets
* The ECM will not illuminate the malfunction indicator lamp (MIL).
* The ECM will store the conditions present when the DTC set as Failure Records data only.
* The ECM will send a class 2 serial data message to the IPC and DIC to illuminate the charge indicator or display a charging message.
Conditions for Clearing the MIL/DTC
* The conditions for setting DTC P0625 are not present.
* The DTC can be cleared by using the scan tool Clear DTC Information function.
Test
