B1488

DTC B1488

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 B1488
- Generator L-Terminal Circuit High - Turn On Signal Circuit




Diagnostic Fault Information






Circuit/System Description

The generator battery control module (GBCM) controls the generator through the generator turn on signal circuit, or L-Terminal circuit. The signal is a 5 volt pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is 0% when the engine is off. If the generator turn on signal circuit is 65 percent or greater duty cycle, or pulled high to positive voltage, when the GEN L-Terminal Signal Command is 0%, then DTC B1488 will set.


Conditions for Running the DTC

* Ignition ON.
* The engine is OFF.
* This diagnostic runs every 100 ms.



Conditions for Setting the DTC

The generator turn on signal circuit is greater than 65 percent or shorted to voltage for 5 seconds.


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 GBCM determines the conditions for setting the DTC are no longer present.
* The charge indicator and SERVICE CHARGSYS message turn off when the conditions for setting the DTC are no longer present.



Reference Information
Schematic Reference

Starting and Charging Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Component Connector End 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)

Scan Tool Reference

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


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the generator.
2. Ignition ON, GEN L-Terminal Signal Command 0%, test for less than 1 volt between the generator turn on signal circuit terminal 1 and ground.

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

3. Command the GEN L-Terminal Signal ON to 80% duty cycle with a scan tool. Test for 3.0 volts between the generator turn on signal circuit terminal 1 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 GBCM.

4. If the circuit tests normal, replace the generator.



Repair Instructions

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

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