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

Diagnostic Fault Information





Circuit/System Description

The generator battery control module (GBCM) controls the generator through the generator turn on signal 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 between 5-95 percent. If the generator turn on signal circuit is 65 percent or greater duty cycle or pulled high to battery positive voltage, 5 volts, then DTC B1488 will set.

Conditions for Running the DTC

* The ignition is in RUN.
* The engine is OFF.
* The engine RPM is 0.
* This diagnostic runs every 100 ms.

Conditions for Setting the DTC

The generator turn on signal circuit is greater than 95 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 BATTERY message.

Conditions for Clearing the DTC

The GBCM determines the fault has cleared.

Diagnostic Aids

You must cycle the ignition after clearing the DTC to turn OFF the BATTERY DIC message and turn OFF the charge indicator.

If a fault condition persists, replace the module.

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 (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the generator.
2. Ignition ON, test for less than 1 volt between the generator turn on signal circuit X1 - 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. Engine Running, test for greater than 3.5 volts between the generator turn on signal and ground.

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

4. If the circuit tests normal during the ignition ON/Run test, replace the generator.

Repair Instructions

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

* Control Module References (Control Module References) for GBCM replacement, setup, and programming
* Generator Replacement (With 4.2L Engine) ()Generator Replacement (5.3L Engine) (Generator Replacement (5.3L Engine))