P2500

DTC P2500

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptor
DTC P2500
- Generator L-Terminal Circuit Low Voltage

Diagnostic Fault Information





Circuit/System Description

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. When the ECM turns ON the high side driver, the voltage regulator turns ON the field circuit. When the ECM turns OFF the high side driver, the voltage regulator turns OFF the field circuit.

The ECM monitors the state of the generator turn on signal circuit. With the engine running, the ECM should detect a high generator turn on signal circuit.

Conditions for Running the DTC

* No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
* The engine is running.

Conditions for Setting the DTC

The ECM detects a low signal voltage on the generator turn on signal circuit for 15 seconds.

Action Taken When the DTC Sets

The instrument panel cluster (IPC) illuminates the charge indicator.

Conditions for Clearing the DTC

DTC P2500 is a C type DTC.

Reference Information
Schematic Reference

Starting and Charging Schematics ([1][2]Electrical Diagrams)
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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X1 at the generator.
2. Engine running, test for greater than 3.5 volts between the generator turn on signal circuit terminal B X1 and ground.

• If less than the specified range, test the generator turn on signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

3. If the circuit tests 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)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming