B3844

DTC B3844

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 Descriptor
DTC B3844
- Heater Core Pump Circuit




Circuit/System Description

The starter/generator control module (SGCM) monitors the heater core pump control circuit for an open wire or a over current condition.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC


B3844
* Eco-back signal (High) does not match to the LSD output signal for 320 ms.
* Eco-back signal (Low) does not match to the LSD output signal for 320 ms.



Action Taken When the DTC Sets

B3844

Set heater core pump validity to invalid.


Conditions for Clearing the DTC


B3844
* LSD over current fault removed.
* Clears 30 seconds after cycle wake up signal.
* LSD wire open fault removed.
* Normal range for 3.5 seconds.



Diagnostic Aids


B3844
* Possible over current or wire shorted to B+.
* Possible wire open or shorted to ground.



Reference Information
Schematic Reference

Hybrid Cooling Schematics ()
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Air Temperature Description and Operation (Air Temperature Description and Operation)
* Air Delivery Description and Operation (Air Delivery 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


Circuit/System Verification

1. Ignition ON, command the heater core pump ON and OFF with a scan tool.
2. Observe the operation of heater core pump.



Circuit/System Testing


B3844
1. Ignition OFF, disconnect the harness connector at the heater core pump.
2. Ignition ON, verify that a test lamp illuminates between the control circuit terminal B and B+, while commanding the pump ON and OFF with a scan tool.

• If the test lamp is always ON, test the control circuit for a short to Ground. If the circuit tests normal, replace the Starter Generator Control Module (SGCM).

3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and control circuit terminal B, while commanding the pump ON and OFF with a scan tool.

• The test lamp should be ON and Off with each commanded state, if the test lamp is always OFF, test the B+ circuit for an open or short to ground. If the test lamp operates properly with each command, replace the heater core pump.




Repair Instructions

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


Control Module References (Programming and Relearning) for SGCM replacement, setup, and programming


Heater Coolant Pump Replacement (LAT) ()