B1390

DTC B1390

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 B1390
^ Device Voltage Reference Input 1 Circuit

Circuit/System Description

The generator battery control module (GBCM) monitors the battery voltage for precision electrical power management. The GBCM monitors both the battery sense positive voltage circuit and the battery sense negative, ground, circuit to precisely determine system voltage. If there is a difference between the less precise battery voltage, battery positive voltage circuit and ground circuit, and the more precise battery sense voltage of 1 volt or greater for 10 seconds, then DTC B1390 will set.

Conditions for Running the DTC

* The ignition switch is in the RUN position.
* This diagnostic runs every 100 ms.

Conditions for Setting the DTC

The difference between the low precision battery voltage circuit reading and the high precision battery voltage sense circuit reading is greater than or equal to 1 volt for 10 seconds.

Action Taken When the DTC Sets

* The GBCM will request the driver information center (DIC) to display the BATTERY message.
* The GBCM uses the less accurate battery positive voltage circuit for voltage readings.

Conditions for Clearing the DTC

During the current ignition cycle, the difference between the less precision battery positive voltage circuit reading and the high precision battery voltage sense circuit reading is less than 1 volt.

Diagnostic Aids

* You must cycle the ignition after clearing the DTC to turn off the BATTERY DIC message.
* Overcharging with a battery charger or jump starting could cause this DTC to set.
* A high voltage value in multiple modules indicates a concern in the charging system.

Reference Information
Schematic Reference

Control Module References (Control Module References)
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 Verification

1. Measure the voltage at the battery terminals.
2. Ignition ON, observe the scan tool GBCM Battery Positive Voltage parameter. The battery terminal voltage and scan tool parameter should not differ by more than 2 volts.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the GBCM.
2. Ignition OFF, test for less than 1.0 ohm between the ground circuit terminals H and F to ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, measure between the battery positive voltage circuit terminals A and C and ground circuit terminals H and F. The readings should not differ by more than 2 volts.

• If greater than the specified value, test the ignition voltage circuit for a short to ground or an open/high resistance.

4. If all circuits tests normal, replace the GBCM.

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.