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 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 system voltage returns to a normal range.
Reference Information
Schematic Reference
Body Control System Schematics (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
Diagnostic Aids
* A high or low voltage DTC set in multiple modules indicates a concern in the charging system.
* A possible cause of this DTC could be overcharging with a battery charger or jump starting.
* A high or low voltage value in multiple modules indicates a concern in the charging system.
Circuit/System Verification
1. Engine running measure and record the voltage at the battery terminals. Verify that the battery voltage is 12.5-15.5 volts.
• If the battery voltage is not within the specified range, refer to Charging System Test (Charging System Test)
2. Engine running, observe the scan tool BCM Battery Positive Voltage parameter. Verify that the scan tool displays a value that is within 2 volts of the battery voltage recorded in step 1.
• If the scan tool parameter is not within the specified range, refer to Circuit/System Testing.
3. Refer to Diagnostic Aids.
Circuit/System Testing
1. Ignition OFF. Disconnect the harness connectors at the BCM. Verify that there is less than 1.0 ohm between the ground circuits X1 17- 19- 20 / X2 50 and the negative battery terminal.
• If greater than the specified value, test the affected ground circuit for an open/high resistance.
2. Ignition ON. Test for 9.5-13.5 volts between the battery positive voltage circuits X1 terminals 50- 51- 52 / ignition 1 circuits X1 terminals 22- 23 and the ground circuit X2 terminal 50 of the BCM.
• If not within the specified range, test the affected battery positive voltage circuits / ignition 1 circuits for a short to ground or an open/high resistance.
3. If all the 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 BCM replacement, setup, and programming.