B1390
DTC B1390
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC B1390
- Device Voltage Reference Input 1 Circuit - GBCM
Circuit/System Description
The generator battery control module (GBCM) monitors the battery voltage for precision electrical power management. The generator battery control module 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 1.5 volts for 7 seconds, then DTC B1390 will set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The difference between the low precision battery voltage reading and the high precision battery voltage reading is greater than 1.5 volts for 7 seconds.
Action Taken When the DTC Sets
* The driver information center (DIC) displays the SERVICE CHARGE SYS 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 1.5 volts.
* The SERVICE CHARGE SYS message will turn off 7 seconds after the voltage returns to normal.
Diagnostic Aids
* A possible cause of this DTC could be overcharging with a battery charger or jump starting.
* A high voltage value in multiple modules indicates a concern in the charging system.
Reference Information
Schematic Reference
Control Module References (Programming and Relearning)
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 volts.
• If not within the specified range, refer to Charging System Test (Charging System Test) .
2. Observe the scan tool BCM Battery Voltage Signal parameter and the Batt. Voltage High Res. parameter. The readings for both parameters should be between 12.6 and 15.0 volts, and should be within 1.5 volts of each other.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connectors at the GBCM.
2. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the ground circuit terminals listed below and ground:
* Terminal F
* Terminal H
• 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 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.