B1420

DTC B1420

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 B1420
- Device Voltage Circuit

Diagnostic Fault Information





Typical Scan Tool Data





Circuit/System Description

The body control module (BCM) monitors the battery voltage on the battery voltage signal circuit. Damage to components, and incorrect data may occur when the voltage is out of range.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

Battery voltage is outside the range of 9-16 V for 1 second.

Action Taken When the DTC Sets

* The BCM will disable its outputs when a high voltage condition is detected.
* The BCM inhibits the setting of other DTCs.

Conditions for Clearing the DTC

The DTC passes when the malfunction is no longer present.

Diagnostic Aids

* Overcharging with a battery charger and jump starting may set this DTC.
* A high or low voltage value in multiple modules indicates a concern in the charging system.

Reference Information
Schematic Reference

Body Control System Schematics ([1][2]Body Control Systems)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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 voltage at the battery voltage at the battery terminals. The voltage should be between 12.6V and 15.0V.

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

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

Circuit/System Testing

1. Ignition OFF, disconnect the harness connectors at the BCM.
2. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5Ohms between the ground circuit terminal B3 X1 and ground.

• 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 A7 X1
* Terminal B5 X1
* Terminal B8 X1

• 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 BCM.

Repair Instructions

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

Control Module References (Programming and Relearning) for the BCM replacement, setup, and programming.