Electric Coolant Pump

Courtesy of VOLVO CARS CORPORATION

The task of the electric coolant pump is to generate flow in the cooling loop between the radiator and the engine so as to keep the engine temperature within the permitted limits, and contribute to the climate system for the passenger compartment maintaining the desired temperature.

The pump is connected to the Engine Control Module (ECM) via LIN and the pump can be controlled steplessly.

On earlier engine versions, the coolant pump is driven mechanically when the engine is running, at a pump speed that varies with engine speed. By instead having electric pump control it can be partly demand controlled at specific operating instances, e.g:

• During the engine's heating sequence the pump and thermostat can be controlled for the fastest possible heating, i.e. small flow and thermostat closed.

• With the engine in autostop mode, the pump can be controlled to the active position and thus temper the engine, as well as contribute to maintaining the passenger compartment temperature.

There is an extra connection between the control module and pump to ensure that the pump can be governed fully or off. This is used in emergency situations if LIN communication is not working. The pump is normally governed fully when LIN is missing.

The pump is powered with 12V through the relay/fusebox engine compartment and grounded at the body frame.

The pump is installed on the engine between the intake manifold and the starter motor.

The pump and communication with the pump are diagnosed by the Engine Control Module (ECM). Parameters for the coolant pump can be read off by the diagnostic tool.