Engine Electrical Coolant Heater
DTC B1424 (Coolant Heater)
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 B1424
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Device 1 Voltage Low
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 10.2 V for 15 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.
Reference Information
Schematic Reference
HVAC Schematics Electrical DiagramsHVAC Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
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 Control Module References for scan tool information
Diagnostic Aids
A low voltage DTC in multiple modules indicates a concern in the charging system.
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 B1424 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 Testing and Inspection.
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.
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 the 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