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• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
B+ | P0622, P0625 | P0622, P0625 | - | - |
Signal | P0622, P0625 | P0622, P0625 | P0622, P0626 | - |
Control | P0621, P2500 | P0621, P2500 | P0621, P2501 | - |
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%.
• | Ignition ON, engine OFF, for the Ignition ON test. |
• | Engine running, engine speed less than 3 000 RPM for the RUN test. |
• | The engine is running. |
• | The engine speed is less than 3 000 RPM. |
• | The engine is not running. |
• | The ignition is in the ON position. |
• | The ECM detects a PWM signal that is greater than 65% for 5 s. |
• | The ECM detects a PWM signal that is less than 5% for 15 s. |
The ECM detects a pulse width modulated (PWM) signal less than 5% for 15 s.
The ECM detects a pulse width modulated (PWM) signal greater than 65% for 15 s.
DTC P0622, P0625 and P0626 are a C type DTCs.
DTC P0622, P0625 and P0626 are a C type DTCs.
Starting and Charging Schematics
Charging System Description and Operation
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
Engine running, observe the scan tool Generator F-Terminal Signal parameter. The Generator F-Terminal Signal parameter should display between 5-99%.
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
⇒ | 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. |
⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Generator Replacement : 2.4L LAF → 1.8L 2H0 → 2.0L Diesel LNP |
• | Control Module References for ECM replacement, setup, and programming |
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