* The vacuum valve is located on the intake manifold.
* It is connected to the vacuum hose that runs from the throttle body to the brake booster.
* The vacuum valve is responsible for controlling the flow of vacuum to the brake booster.
* When the engine is running, the vacuum valve opens and allows vacuum to flow to the brake booster.
* When the engine is turned off, the vacuum valve closes and prevents vacuum from flowing to the brake booster.
This diagram shows the location and function of the vacuum valve on a 1992 Isuzu 3.1-liter 4WD:
[Image of vacuum valve diagram]