How does a modulator valve work?
What is a modulator valve? A modulator valve is found in automatic transmissions to shift gears depending upon the load on the engine. Its vacuum line is attached to the intake which measures the amount of vacuum in the system. When the gas pedal is pushed, the throttle plate opens and the vacuum is released.
Which of the following are symptoms of a leaking vacuum modulator?
When you have a bad modulator valve, some or all of the following symptoms will begin to manifest themselves:
- A whistling sound (from a leaking diaphragm)
- White smoke coming out of the exhaust (from a leaking diaphragm)
- Early or late shifting.
- Hard shifts (usually causing the car to jerk)
- A rough idle.
What is the purpose of a modulation valve in a transmission?
The modulator valve is attached to the intake manifold with a vacuum line. It senses intake manifold vacuum and shifts the transmission accordingly: When you press down on the gas pedal, the throttle plate opens and the vacuum is reduced. The modulator valve will cause the transmission to downshift.
What is modulator pressure?
Vacuum Modulator is an engine load sensing device that converts engine vacuum into a transmission valve body input. Many vacuum modulators also allow for tuning via a small blade screw driver that turns the thread to increase or decrease spring pressure against a diaphragm inside.
Can vacuum leak cause transmission problems?
The transmission can be controlled. A vacuum leak will cause the engine performance to suffer, causing load and throttle position issues which could affect transmission shifting.
How does the transmission vacuum modulator valve work?
by Greg Day. The transmission vacuum modulator valve determines how much load is on the engine so the transmission can shift properly. It has a vacuum line that connects to the intake and measures the amount of vacuum in the engine.
What kind of modulator does a transmission use?
Today’s transmissions use solenoids for shift timing. Throttle pressure indicates engine load. Some transmissions use a vacuum modulator or throttle linkage to control the throttle valve. Late model vehicles use electric solenoids to achieve the same results.
How does the modulator valve measure engine load?
It has a vacuum line that connects to the intake and measures the amount of vacuum in the engine. In order to determine if whether transmission should shift, the modulator valve measures the load of the engine’s vacuum. Engine load is the measurement of how hard an engine works at any given moment.
What happens if the modulator valve is not working?
If the modulator valve is not working properly, the transmission will not shift properly. These problems can arise when the hose connecting the transmission to the engine vacuum cracks or burns, or collapses onto itself.