Control After Start

WARNING: This page is about a different variant/trim than selected.

After engine start, ECM turns ON the coolant pump Switchover valve to turn OFF the coolant pump. This stops the coolant circulation.

Courtesy of NISSAN NORTH AMERICA, INC.

ECM controls the coolant Switchover valve to adjust negative pressure on the vacuum actuator installed to the coolant pump. Via the vacuum actuator rod, ball rotary valve is closed allowing the coolant flow to be stopped. This stops coolant to flow to the cylinder head.

	Belt pulley
	Coolant pump housing

When all of the following conditions are satisfied, ECM performs the cold start control to deactivate the coolant pump.

Engine coolant temperature: 85°C (185°F) or less
Charge air temperature: below threshold limit
Engine speeds: 4000 RPM or less
No heater request from A/C auto amp.

When coolant pump stop conditions are not satisfied, ECM turns OFF the coolant pump Switchover valve. Negative pressure on the coolant pump Switchover valve is ventilated through the air vent. The spring force returns the ball rotary valve in the direction flowing coolant. This turns ON the coolant pump, allowing coolant circulation again.