B1487

DTC B1487

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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 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 in the 0-5 percent range, pulled low to ground or open then DTC B1487 will set.

Conditions for Running the DTC

* The engine speed is greater than 450 RPM.
* This diagnostic shall be run every 100 ms.

Conditions for Setting the DTC

The generator turn on signal circuit is less than or equal to 5 percent duty cycle for more than 120 seconds.

Action Taken When the DTC Sets

* The charge indicator illuminates on the instrument panel cluster (IPC).
* The driver information center (DIC) displays the BATTERY message.

Conditions for Clearing the DTC

The generator turn on signal circuit input is from 5-95 percent duty cycle, greater than 0 volts.

Circuit/System Testing

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

3. 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.

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

Repair Instructions

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

* Generator Replacement (With 4.2L Engine) Generator Replacement (With V8 Engine)