B1425

DTC B1425

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 B1425
- Device 1 Voltage High

Diagnostic Fault Information





Circuit/System Description

The Heater Coolant Heater Control Module (HCHCM) monitors the system voltage to ensure that the voltage stays within the proper range. Damage to components, and incorrect data may occur when the voltage is out of range.

Conditions for Running the DTC

* The voltages supplied to the control module is between 9.5-18 V.
* The ignition is ON.
* The engine is running.

Conditions for Setting the DTC

HCHCM detects a system voltage below 16 V for 5 seconds.

Action Taken When the DTC Sets

The control module immediately disables all outputs when an out of range voltage condition has been detected.

Conditions for Clearing the DTC

The DTC clears when the system voltage returns to a normal range.

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

HVAC Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Air Temperature Description and Operation (Air Temperature)
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)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Observe the scan tool Auxiliary Heater Control Module, System Voltage High, System Voltage Low, DTC Set This Ignition parameters will assist you to verify if the fault is present.
2. Verify that DTC B1425 is set as current.
3. Engine running measure and record the voltage at the battery terminals.
4. Verify that the battery voltage is 12.6-15.5 V.

• If the battery voltage is not within the specified range, refer to Charging System Test (Charging System Test)

5. Observe the scan tool Auxiliary Heater Control Module ignition signal parameter.
6. The battery terminal and AHCM parameter should not differ by more than 2 V.

• If greater than specified value, replace the Heater Coolant Heater Control Module.

Repair Instructions

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

Heater Coolant Heater Control Replacement (Service and Repair)