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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

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 battery sense positive voltage circuit and the battery sense negative, or ground, circuit to precisely determine system voltage. If there is a difference between the less precise battery voltage circuit and the more precise battery sense circuit of 1 volt or greater for 10 seconds, then DTC B1390 will set.

Conditions for Running the DTC

* The ignition is ON.
* 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 driver information center (DIC) displays the BATTERY message.
* The GBCM uses the less accurate battery positive voltage circuit for voltage readings.

Conditions for Clearing the DTC

This DTC will pass when 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

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 (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 (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 volts.

If not within the specified range, refer to Charging System Test (Testing and Inspection).

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

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the GBCM.
2. Ignition OFF, scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the following ground circuit terminals and ground:

* Terminal F
* Terminal H

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

3. Ignition ON, verify that a test lamp illuminates between the following B+ circuits 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 test 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.