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 SGCM starter generator control module controls the auxiliary cooland pump. Heater core coolant pump relay supplies voltage to the heater core coolant pump.

Control circuit over current

Set heater core pump validity to invalid.

Schematic Reference

Hybrid Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Air Delivery Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

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

1. Ignition OFF, disconnect the harness connector at the heater core coolant pump.
2. Ignition ON, verify that a test lamp illuminates between the control circuit terminal B and ground 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 voltage. If the circuit tests normal, replace the SGCM.

3. Verify that a test lamp illuminates between the B+ circuit terminal A and ground.

⇒	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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.