Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DECEL Throttle Modulator: Operation
Manifold vacuum is routed through a Ported Vacuum Switch (PVS) and a solenoid vacuum valve. The solenoid vacuum valve is normally closed to the vacuum throttle modulator. Power is available to solenoid vacuum valve through an electronic sensor. Electronic sensor ground circuit is normally open. As engine reaches 1850 RPM, ground circuit in sensor is completed allowing solenoid vacuum valve to open. Vacuum pulls throttle modulator diaphragm which pushes throttle to high idle position during deceleration. Engine coolant must be above 125°F before PVS will allow vacuum to reach solenoid vacuum valve.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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