Chart C-2D, Secondary Port Throttle Valve System Check

Chart C-2D, Secondary Air Inlet Valve System Check:

Secondary Port Throttle Valve System Control Circuit Diagram:

CIRCUIT DESCRIPTION
The secondary port throttle valve system is used to allow the intake of air and fuel through the secondary intake valves during high engine speed and load conditions (when the engine power mode switch is in the "FULL" position). A vacuum sensor is used to determine if the secondary port throttle valve system is operating properly.

A computer controlled vacuum solenoid valve is used to apply vacuum to open the secondary throttle valve actuators when the system is in "FULL" power mode, and vent the actuator diaphragms to close the throttle valves when in "NORMAL power mode. During "NORMAL" operation, there should be no vacuum at the actuators and the voltage signal from the vacuum sensor should be 0.54 - 0.62 volts. During "FULL" power operation, vacuum is applied to the secondary port throttle valve actuators and the sensor signal should be 1.3 - 3.1 volts, indicating vacuum at the actuators. The PCM monitors the signal from the vacuum sensor and compares that information with the commanded status of the system. If the system is in "NORMAL" mode, and the vacuum sensor signal indicates vacuum is being applied to the actuators, a code 61 will set. If the system is in "FULL" power mode and there is no indication of vacuum at the actuators, a code 61 will also set. If at any time the signal from the vacuum sensor is greater than 4.8 volts or less than 0.46 volt, a code 56 will set.

TEST DESCRIPTION
Numbers below refer to circled numbers on diagnostic chart.
1. When "field service mode" is selected on the scan tool, the PCM will energize the secondary port throttle valve solenoid, allowing vacuum to the actuators and vacuum sensor. Turning the ignition "ON", will energize the electric vacuum pump and should maintain 57 kPa (17" Hg) vacuum in the reservoir tank.
2. The electric vacuum pump should operate with the ignition "ON" whenever the vacuum at the pump is less than 41 kPa (12" Hg), causing a switch in the pump to turn the pump "ON". With the engine not running, there is no manifold vacuum available, and the pump should run.
3. When the vacuum fitting on the pump is plugged the pump should shut off as soon as its internal vacuum reaches a predetermined level.

DIAGNOSTIC AIDS
If the secondary port throttle valve system has a vacuum leak, check for disconnected vacuum hoses, leaking check valves or fittings. Check the vacuum hoses under the plenum for cracks, splits, and incorrect routing.

the secondary port throttle valve system will only operate if the vehicle system voltage is greater than 10 volts, and both coolant and oil temperature sensors indicate between 20°C - 151°C (68°F - 304°F.) Faulty CTS or EOT sensor can cause erratic operation.