DTC P0621
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Perform
the Diagnostic
System Check - Vehicle prior to using this diagnostic procedure. |
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Review
Strategy
Based Diagnosis for an overview of the diagnostic approach. |
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Diagnostic
Procedure Instructions provides an overview of each diagnostic category. |
DTC P0621: Generator
L-Terminal Circuit
The engine control
module (ECM) uses the generator turn on signal 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 signals the voltage regulator to turn the field
circuit ON and OFF. The ECM monitors the state of the generator turn on signal
circuit. The ECM should detect low voltage on generator turn on signal 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 signal circuit. The ECM performs key ON and RUN tests to determine the
status of the generator turn on signal circuit.
Conditions
for Running the DTC
Key
ON Test
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No
generator, crankshaft position (CKP) sensors, or camshaft position (CMP)
sensor DTCs are set. |
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The
ignition is in RUN position. |
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The
engine is not running. |
Run
Test
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No
generator, CKP sensors, CMP sensor DTCs are set. |
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The
engine is running. |
Conditions
for Setting the DTC
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During
the key ON test, the ECM detects high voltage on the generator turn on signal
circuit for at least 5 seconds. |
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During
the RUN test, the ECM detects low voltage on the generator turn on signal
circuit for at least 15 seconds. |
Action
Taken When the DTC Sets
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The
ECM will command the charge indicator and or warning message to be
illuminated on the instrument panel cluster (IPC) and the driver information
center (DIC), if equipped. |
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The
ECM will not illuminate the malfunction indicator lamp (MIL). |
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The
ECM will store conditions, which were present when the DTC set as Failure
Records data only. |
Conditions
for Clearing the DTC
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The
history DTC will clear after 40 consecutive warm-up cycles have occurred
without a malfunction. |
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Using
the scan tool Clear DTC Information function can clear the DTC. |
On vehicles equipped
with a sense circuit connected to the voltage regulator.This
circuit must have voltage for the charging system to operate properly.This circuit is used as a reference to control
system voltage. All circuits must be tested at the generator before replacing
any components. refer to system schematic to confirm
if the vehicle being serviced uses the sense circuit as part of the charging
system.
Schematic
Reference
Starting
and Charging Schematics
Connector
End View Reference
Engine
Electrical Connector End Views
Electrical
Information Reference
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Scan
Tool Reference
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Scan
Tool Data List for ECM |
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Scan
Tool Data Definitions for ECM |
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If
less than the specified range, test the generator sense circuit for a short
to ground, an open/high resistance. |
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If
greater than the specified range, test the generator turn on signal circuit
for a short to voltage. If the circuit tests normal, replace the ECM. |
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If
less than the specified range, test the generator turn on signal circuit for
a short to ground, an open/high resistance. If the circuit tests normal,
replace the ECM. |
Perform the Diagnostic
Repair Verification after completing the diagnostic procedure.
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Control
Module References for ECM replacement, setup, and programming |
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