P2500

DTC P2500

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 P2500
- Generator L-Terminal Circuit Low

Diagnostic Fault Information





Circuit/System Description

The engine control module (ECM) uses the generator turn on signal circuit, or L-terminal 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 tests to determine the status of the generator turn on signal circuit.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The ECM detects low voltage on the generator turn on signal circuit for 2 seconds.


Action Taken When the DTC Sets

The charge indicator turns ON 15 seconds after the DTC sets.

Conditions for Clearing the DTC

* The DTC will pass when the conditions for setting the DTC are no longer met for 2 seconds.
* A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
* The charge indicator turns OFF 15 seconds after the DTC passes.

Reference Information
Schematic Reference

Starting and Charging Schematics ()
Connector End View Reference

Component Connector End Views (Connector Views)
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

Programming and Relearning (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the generator.
2. Ignition ON, engine OFF, test for less than 1 V between the signal circuit terminal B and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

3. Engine running, test for greater than 3 V between the signal circuit terminal B and ground.

• 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 ECM.

4. If all circuits test normal, test or replace the generator.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Generator Replacement (Service and Repair)
* Programming and Relearning (Programming and Relearning) for ECM replacement, setup, and programming.