Variable Coolant Pump
| ITEM | DESCRIPTION |
|---|---|
| 1 | Electrical connector - Power supply and Powertrain Control Module (PCM) control |
| 2 | Electrical connector - Pulse Width Modulation (PWM) and position reference |
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 5 steps and is controlled by an open-loop map.
The shroud solenoid is controlled 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 held at its default position (flow mode 4) by the return spring force. This results full coolant flow from the pump.
Flow modes:
- = Zero flow
- = 12% flow
- = 25% flow
- = 50% flow
- = 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 4 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.