DTC B3844 with HP5
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B3844: Heater Core Pump CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Heater Core Coolant Pump Control | B3844 | B3844 | B3844 | -- |
Heater Core Coolant Pump voltage | -- | B3844 | -- | -- |
Circuit/System Description
The primary purpose of the heater core coolant pump is to circulate engine coolant through the HVAC heater core when heat is required in the cabin for comfort. This normally happens when the vehicle is in an Auto Stop and the mechanical pump is not spinning. If the HVAC control module has determined heat is needed for the cabin, this pump is turned on once the engine is shut off so the customer does not notice a change in heater duct discharge temperatures.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
| • | The HVAC module is ON. |
Conditions for Setting the DTC
Control circuit over current
Action Taken When the DTC Sets
Set heater core pump validity to invalid.
Conditions for Clearing the DTC
| • | Over current fault removed. |
| • | Clears 30 seconds after cycle wake up signal. |
| • | Open fault removed. |
| • | Normal range for 3.5 seconds. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Air Delivery Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, command the heater core pump ON and OFF with a scan tool.
- Observe the operation of heater core pump.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the heater core coolant pump.
- Verify that a test lamp illuminates between the B+ circuit terminal A and ground.
- Ignition ON, verify that a test lamp illuminates between the control circuit terminal B and the voltage circuit terminal A while commanding the pump ON and OFF with a scan tool.
| ⇒ | If the test lamp does not light, test the B+ circuit for a short to ground, open or high resistance. If the circuit tests normal, replace the Coolant heater pump |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for HVAC control module replacement, setup, and programming |
DTC B3844 with HP7
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B3844: Heater Core Pump CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Heater Core Coolant Pump Control | B3844 | B3844 | B3844 | -- |
Heater Core Coolant Pump Ground | -- | B3844 | -- | -- |
Circuit/System Description
The primary purpose of the heater core coolant pump is to circulate engine coolant through the HVAC heater core when heat is required in the cabin for comfort. This normally happens when the vehicle is in an Auto Stop and the mechanical pump is not spinning. If the HVAC control module has determined heat is needed for the cabin, this pump is turned on once the engine is shut off so the customer does not notice a change in heater duct discharge temperatures. The starter generator control module controls the auxiliary cooland pump.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
| • | The HVAC module is ON. |
Conditions for Setting the DTC
Control circuit over current
Action Taken When the DTC Sets
Set heater core pump validity to invalid.
Conditions for Clearing the DTC
| • | Over current fault removed. |
| • | Clears 30 seconds after cycle wake up signal. |
| • | Open fault removed. |
| • | Normal range for 3.5 seconds. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Air Delivery Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, command the heater core pump ON and OFF with a scan tool.
- Observe the operation of heater core pump.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the heater core coolant pump.
- Verify that a test lamp illuminates between the B+ circuit terminal A and ground.
- Ignition ON, verify that a test lamp illuminates between the control circuit terminal B and the ignition voltage terminal A while commanding the pump ON and OFF with a scan tool.
| ⇒ | If the test lamp does not light, test the B+ circuit for a short to ground, open or high resistance. If the circuit tests normal, replace the coolant heater pump |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the Starter Generator Control Module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for Starter Generator Control Module replacement, setup, and programming |
