DTC P0622
DTC P0622 |
Diagnostic Instructions |
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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.
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DTC Descriptor |
DTC P0622
Generator F-Terminal Circuit
Diagnostic Fault Information |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
B+
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P0622
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P0621
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-
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-
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Control
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P0621
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P0621
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P0621
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-
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Signal
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P0622
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P0622
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-
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P0622
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Circuit/System Description |
The engine control module (ECM) uses the generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to high side of the field windings in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field windings 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 status of the generator field duty cycle signal circuit. When the ignition is ON and the engine is OFF, the ECM should detect a duty cycle near 0%. When the engine is running, the duty cycle should be between 5-99%.
Conditions for Running the DTC |
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Ignition ON engine OFF, for the Ignition ON test.
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Engine running, engine speed less than 3 000 RPM for the RUN test.
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Conditions for Setting the DTC |
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DTC P0621 is not set.
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Ignition ON engine OFF, the ECM detects a PWM signal that is greater than 65% for 5 seconds.
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Engine running, the ECM detects a PWM signal that is less than 5% for 15 seconds.
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Action Taken When the DTC Sets |
DTC P0622 is a C type DTC.
Conditions for Clearing the DTC |
DTC P0622 is a C type DTC.
Reference Information |
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
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification |
Engine running, observe the scan tool Generator F-Terminal Signal Circuit parameter. The Generator F-Terminal Signal Circuit parameter should display between 5-99%.
Circuit/System Testing |
1. |
Verify that a test lamp illuminates between the G13 Generator B+ terminal A X1 and ground.
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2. |
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. |
Ignition OFF, disconnect the X2 harness connector at the G13 Generator.
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4. |
Ignition ON, verify the scan tool Generator F-Terminal Signal parameter displays less than 5%.
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5. |
If greater than the specified range, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
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6. |
Install a 3 A fused jumper wire between B+ and the signal circuit terminal 2.
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7. |
Verify the scan tool Generator F-Terminal Signal parameter displays greater than 95%.
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8. |
If less than the specified range, test the signal circuit terminal 2 for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
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9. |
If the circuit tests normal replace the G13 Generator.
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Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Refer to
Generator Replacement (Diesel)
Generator Replacement (LAU/A28NER)
Generator Replacement (LLU/A16LET)
Generator Replacement (LHU/A20NFT)
.
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Control Module References
for ECM replacement, setup, and programming
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