P0621
DTC P0621
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0621
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Generator L-Terminal Circuit
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) uses the generator turn ON control circuit to control the load of the generator on the engine. A high side driver in the ECM applies a voltage to the voltage regulator. This controls the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn ON control circuit. The ECM should detect low voltage on generator turn on control circuit when the ignition is ON and the engine is OFF, or when the charging system malfunctions. With the engine running, the ECM should detect high voltage on the generator turn on control circuit.
Conditions for Running the DTC
* The ignition ON, engine OFF for ignition on test.
* The engine is running for the run test.
Conditions for Setting the DTC
* During the ignition on test, the ECM detects voltage on the generator turn on control circuit for 5 s.
* During the run test, the ECM detects low voltage on the generator turn on control circuit for 15 s.
Action Taken When the DTC Sets
DTC P0621 is a C type DTC.
Conditions for Clearing the DTC
DTC P0621 is a C type DTC.
Reference Information
Schematic Reference
Starting and Charging Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Charging System Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Verify that a test lamp illuminates between the G13 Generator B+ output circuit terminal 1 X1 and ground.
• If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
2. Ignition OFF, disconnect the X1 harness connector at the G13 Generator and the appropriate harness connector at the K20 Engine Control Module.
3. Test for less than 5 ohms between the X1 harness connector L-terminal and the appropriate harness connector at the K20 Engine Control Module as listed below:
* Terminal 21 X2 (LBQ, LBR and LBS)
* Terminal 14 X2 (LBY)
* Terminal 47 X3 (LUJ)
* Terminal 53 X2 (LHU)
* Terminal 10 X1 (LBW)
* Terminal 33 X2 (LLU)
* Terminal 1 X1 (2H0 and LDE)
• If not the specified value, test the L-terminal circuit for an high/open resistance.
4. Test for infinite resistance between the G13 Generator harness connector L-terminal and ground.
• If less than the specified range, test for short to ground or a short to voltage.
5. Connect the harness connector at the K20 Engine Control Module.
6. Adapt the G13 Generator F-terminal to the X1 harness connector F-terminal.
7. Engine run at 2 500 RPM, verify the C1 Battery voltage is 12.6-15 V.
• If not the specified value, refer to Charging System Test Testing and Inspection. If the circuit tests normal, test the G13 Generator before replacing.
8. If the circuit tests normal, replace the K20 Engine Control Module.
Component Testing
Dynamic Test
1. Connect a oscilloscope at the G13 Generator terminal B+ X2 and the G13 Generator housing.
2. Engine run at 2 500 RPM.
3. Compare the pictured signal with the following references Generator Oscilloscope Information Component Tests and General Diagnostics.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Generator Replacement (LE9) Generator Replacement (LE9)Generator Replacement (LF1) Generator Replacement (LF1)
* Control Module References Control Module References for ECM replacement, programming and setup