B1439

DTC B1439

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 B1439
- Intermittent Device Voltage Range Performance

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 intermittent system voltage concern.

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.

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)

Scan Tool Reference

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

Diagnostic Aids

* A high or low voltage DTC 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 voltage value in multiple modules indicates a concern in the charging system.
* Inspect G400 for corrosion and proper torque.

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 B1439 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.
7. Ensure the harness connections at the module are fully seated and secure, inspect for bent terminals and corrosion.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the Heater Coolant Heater Control Module (HCHCM).
2. Ignition OFF, test for less than 3.0 Ohms between the ground circuit terminal H X2 and ground.

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

3. Ignition ON, verify a test lamp illuminates between the B+ voltage circuit terminal A X2 and ground.

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

4. If all circuits test normal, 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)