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 00
- Device Voltage Circuit

Diagnostic Fault Information





Circuit/System Description

The auxiliary gauge module monitors the battery voltage through 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 voltage supplied to the auxiliary gauge module is in the range of 7-26 V.
* The ignition is ON.
* The engine is running.

Conditions for Setting the DTC

* The auxiliary gauge module senses a battery voltage above or below the specified range of 9-16 V.
* The above condition lasts for 1 second.

Action Taken When the DTC Sets

* The auxiliary gauge module 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.

Diagnostic Aids

* A high or low voltage DTC set or voltage value 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.

Reference Information
Schematic Reference

Instrument Cluster Schematics (Instrument Cluster Schematics)
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 measure and record the voltage at the C1 battery terminals. Verify that the battery voltage is 12.6-15.0 V.

• 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 P26 auxiliary gauge module Battery Positive Voltage parameter. Verify that the scan tool displays a value that is within 2 V of the battery terminal voltage.

Circuit/System Testing

1. Ignition OFF. Disconnect the harness connectors at the P26 auxiliary gauge module.
2. Ignition OFF, test for less than 5.0 ohm between the ground circuit terminal 2 and ground.

• If greater than the specified value, test the ground circuits for an open/high resistance.

3. Ignition ON, verify a test lamp between the B+ circuit terminal 1 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. If all the circuits test normal, replace the P26 auxiliary gauge module.

Repair Instructions

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

Control Module References (Programming and Relearning) for multifunction auxiliary gauge module replacement, setup, and programming