B1420

DTC B1420

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 B1420
- Device Voltage Circuit




Diagnostic Fault Information






Circuit/System Description

The body control module (BCM) monitors the battery voltage through the battery voltage signal circuit. If the BCM senses that battery voltage is outside of its normal range, DTC B1420 will set. Damage to components, and incorrect data may occur when the voltage is out of range.


Conditions for Running the DTC

* The voltage supplied to the BCM are in the range of 7-26 volts.
* The ignition is ON.
* The engine is running.



Conditions for Setting the DTC

* The BCM senses a battery voltage above or below the specified range of 9-16 volts.
* The above condition lasts for at least 1 second.



Action Taken When the DTC Sets

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



Conditions for Clearing the DTC

The DTC clears when the malfunction is no longer present.


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


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.



Circuit/System Verification

Ignition ON and engine running, observe the battery voltage input parameter in the body control module (BCM) input data list.The reading should be between 9-18 volts.


Circuit/System Testing

1. If the DTC is history, refer to Charging System Test (Charging System Test)
2. Ignition On and the engine running, test for 9.5-17.5 volts between the battery positive voltage and the ground circuits of the BCM.

• If not within the specified range test the B+ circuits for a short to ground or an open/high resistance, and the ground circuits for a open/high resistance.

3. If all the circuits test normal, test or replace the BCM.



Repair Instructions

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


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