DTC P0621, P2500, or P2501
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DTC P0621, P2500, or P2501
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DTC P0621
Generator L-Terminal Circuit
DTC P2500
Generator L-Terminal Circuit Low Voltage
DTC P2501
Generator L-Terminal Circuit High Voltage
Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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B+
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-
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P0621
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-
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-
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Control
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P0621, P2500**
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P0621, P2500**
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P0621, P2501**
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-
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Signal
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P0622*, P0625**
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P0622*, P0625**
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P0622*, P0626**
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P0622*, P0625**
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* LF1
** LAU
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Circuit/System Description
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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
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P0621 and P2500
Engine is running.
P0621 and P2501
Conditions for Setting the DTC
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P0621
•
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During the ignition on test, the ECM detects voltage on the generator turn on control circuit for 5 seconds.
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•
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During the run test, the ECM detects low voltage on the generator turn on control circuit for 15 seconds.
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P2500
The ECM detects low voltage on the generator turn on control circuit for 2 seconds.
P2501
The ECM detects high voltage on the generator turn on control circuit for 2 seconds.
Action Taken When the DTC Sets
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The charge indicator turns ON 15 seconds after the DTC sets.
Conditions for Clearing the DTC
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•
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The DTC will pass when the conditions for setting the DTC are no longer met for 2 seconds.
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•
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A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
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•
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The charge indicator turns OFF 15 seconds after the DTC passes.
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Schematic Reference
Starting and Charging Schematics
Connector End View Reference
Component Connector End Views
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
LAU Engine
1.
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Verify that a test lamp illuminates between the G13 generator B+ terminal A X2 and ground.
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2.
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If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
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3.
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Ignition OFF, disconnect the X1 harness connector at the G13 generator.
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4.
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Ignition ON, test for less than 1 V between the control circuit terminal 1 and ground.
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5.
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If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
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6.
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Engine running, test for greater than 3.5 V between the control circuit terminal 1 and ground.
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7.
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If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
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8.
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If the circuit tests normal, replace the G13 generator.
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LF1 Engine
1.
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Verify that a test lamp illuminates between the G13 generator B+ terminal A X2 and ground.
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2.
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If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
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3.
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Ignition OFF, disconnect the X1 harness connector at the G13 generator.
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4.
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Ignition ON, test for 4.5-5.5 V between the control circuit terminal 1 and ground.
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5.
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If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
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6.
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If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the K20 ECM.
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7.
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If the circuits test normal, replace the G13 generator.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.