Variable Coolant Pump

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

The variable coolant pump is located on the upper left side of the engine within a cavity in the cylinder block. The variable coolant pump comprises a solenoid controlled shroud. The shroud is controlled by the Powertrain Control Module (PCM) to determine the coolant flow required for engine operating parameters.

The PCM receives input signals to determine the required level of cooling.

Inputs are received from:

• Cylinder head temperature sensor
• Exhaust Gas Recirculation (EGR) temperature sensors
• Ambient Air Temperature (ATT) sensor
• Engine Coolant Temperature (ECT) sensors
• Drive mode
• Minimum flow map.

The calibration is able to control the variable coolant pump flow in five steps and is controlled by an open-loop map.

The control of the shroud solenoid is by a Pulse Width Modulation (PWM) signal from the PCM. The internal pressure within the pump acts against a return spring in the housing. Without a signal from the PCM the solenoid is de-energized. The shroud is at its default position (flow mode 4) held under return spring force, resulting in full flow from the pump.

Flow modes:

• 0 = Zero flow
• 1 = 12% flow
• 2 = 25% flow
• 3 = 50% flow
• 4 = Full flow (default position).

During an engine cold start, the impeller is fully covered by the shroud (flow mode 0), therefore no coolant is circulated through the cylinder block. As the engine coolant temperature increases, the flow requirement will increase in four stages (flow mode 1-4).

The variable coolant pump is controlled by the PCM to provide the minimum flow to support all cooling requests from the engine systems. When the engine coolant temperature reaches 85°C (185°F), the solenoid is de-energized. The shroud will move to its default fully open position (flow mode 4) allowing maximum circulation through the cylinder block. Temperature control and flow is then managed by the PCM and the electric thermostat.