B Series Truck 4WD L4-2606cc 2.6L SOHC (1992)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
Checking Bypass Air Control Valve
PURPOSE
Controls idle speed by means of temperature sensitive air valve and ECU controlled idle speed control valve (ISC).
LOCATION
On throttle body.
OPERATION
The ISC valve is ECU controlled, permitting adjustments according to various operating conditions. The air valve is temperature sensitive,
allowing additional measured air to bypass the throttle valves for cold start fast idle. When the valve is cold (cold engine), the air passage is open.
As the valve is warmed by engine coolant, a thermowax capsule expands against the valve, closing off the air passage. Idle speed is then ECU
controlled through signals to the ISC valve.
CONSTRUCTION
BAC valve consists of ECU controlled ISC valve and temperature sensitive air valve.
