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 - GBCM RVC VSENSE B+

Diagnostic Fault Information





Typical Scan Tool Data





Circuit/System Description

The generator battery control module (GBCM) monitors the battery voltage for precision electrical power management. The GBCM monitors both the RVC PWR B+ circuit and the RVC VSENSE B+ circuit to precisely determine system voltage. If the RVC VSENSE B+ circuit is 1.5 V less than the RVC PWR B+ circuit for 7 seconds, then DTC B1390 will set.

Conditions for Running the DTC

This diagnostic runs every 100 ms.

Conditions for Setting the DTC

The RVC VSENSE B+ circuit is 1.5 V less than the RVC PWR B+ circuit for 7 seconds

Action Taken When the DTC Sets

* The GBCM will request the driver information center (DIC) to display the SERVICE CHARGSYS message.
* The GBCM uses the less accurate RVC PWR B+ 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 1.5 V.
* The SERVICE CHARGSYS DIC message will turn off 7 seconds after the voltage on the RVC VSENSE B+ circuit returns to normal.

Diagnostic Aids

* Inspect the RVC PWR and RVC VSENSE fuses for opens.
* Inspect ground G102. Verify that it is clean and tight.

Reference Information
Schematic Reference

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

Component Connector End Views (Connector 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 Verification

1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 V.

• If not within the specified range, refer to Charging System Test (Component Tests and General Diagnostics).

2. Observe the scan tool GBCM Battery Voltage Signal parameter. The reading should be between 12.6 and 15.0 V.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the GBCM.
2. Ignition OFF, test for less than 6.5 Ohms between the ground circuit terminals listed below and ground.

* Terminal H
* Terminal F

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

3. Verify that a test lamp illuminates between the B+ circuit terminals listed below and ground.

* Terminal A
* Terminal C

• If the test lamp does not illuminate, test the B+ 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 (Programming and Relearning) for GBCM replacement, setup, and programming