B1487

DTC B1487

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 B1487
- Generator L-Terminal Circuit Low

Diagnostic Fault Information





Circuit/System Description

The generator battery control module (GBCM) controls the generator through the turn on signal circuit, or L-Terminal circuit. The signal is a 5 V pulse width modulation (PWM) signal of 128 hz. Normal duty cycle when the engine is running is 5-100 percent.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The generator turn on signal is less than 5 percent duty cycle for 2 minutes.

Action Taken When the DTC Sets

* The charge indicator turns ON.
* The driver information center (DIC) displays the SERVICE CHARGSYS message.

Conditions for Clearing the DTC

* The DTC will pass when the generator turn on signal is greater than 5 percent duty cycle.
* The charge indicator and SERVICE CHARGSYS message will remain ON until the ignition switch is cycled after the DTC is cleared.

Reference Information
Schematic Reference

Starting and Charging Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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)

Scan Tool Reference

Control Module References (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, GEN L-Terminal Signal Command 0%, test for less than 1 V between the signal circuit terminal 1 and ground.

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

3. Engine running, command the GEN L-Terminal Signal ON to 80% duty cycle with a scan tool. Test for greater than 3 V between the signal circuit terminal 1 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 GBCM.

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 (LLR) (Service and Repair)Generator Replacement (LH8) (Service and Repair)
* Control Module References (Programming and Relearning)for GBCM replacement, setup, and programming.