P0621
DTC P0621
Circuit Description
The engine control module (ECM)/powertrain control module (PCM) uses the generator turn on signal circuit to control the load of the generator on the engine. A high side driver in the ECM/PCM applies a voltage to the voltage regulator. When the ECM/PCM turns ON the high side driver, the voltage regulator turns ON the field circuit. When the ECM/PCM turns OFF the high side driver, the voltage regulator turns OFF the field circuit.
The ECM/PCM monitors the state of the generator turn on signal circuit. With the engine running, the ECM/PCM should detect a high generator turn on signal circuit, or when the charging system malfunctions. If the ECM/PCM detects a low generator turn on signal circuit DTC P0621 will set. When the DTC sets, the ECM/PCM will send a class 2 serial data message to the instrument panel cluster (IPC) to illuminate the charge indicator.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0621 Generator L-Terminal Circuit
Conditions for Running the DTC
Key ON Test
* The key is in the ON position for 5 seconds.
* The engine is OFF.
Engine Run Test
* The engine is running.
* The engine speed is less than 3,000 RPM.
Conditions for Setting the DTC
During key ON test, the ECM/PCM detects a high signal voltage on the generator turn on signal circuit for at least 5 seconds.
During the RUN test, the ECM/PCM detects a low signal voltage on the generator turn on signal circuit for at least 10 seconds.
Action Taken When the DTC Sets
* The ECM/PCM sends a class 2 message to the IPC to illuminate the charge indicator.
* The ECM/PCM will not illuminate the malfunction indicator lamp (MIL).
* The ECM/PCM will store the conditions present when the DTC set as Fail Records data only.
* The Service Vehicle Soon (SVS) light may be illuminated.
Conditions for Clearing the MIL/DTC
* The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
* The DTC can be cleared by using the scan tool Clear DTC Information function.
Test
