Quote:
Originally Posted by gamefreakgc
Also, some years have a little one-way valve on the booster vacuum hosing that I think goes to the 4WD VSV. These little guys have been know to fail once in a while and cause bad pedal feel. Easy to check them, just take it out and blow in it, air should pass through one way and not the other.
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All of the vacuum booster 4Runners (2WD or 4WD) have a 1-way valve to the booster (actually, all modern vacuum boosters have valves, sometimes internal to the booster assembly). That's what holds vacuum for a couple brake applications if the engine turns off while driving.
There is a separate 1-way valve for the ADD vacuum system, that's the little black/blue thing in the vacuum line down to the ADD VSVs. There is also the vacuum reservoir in the fender well to help with ADD switching. That's only on the pre-01 4Runners.
-Charlie
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'99 4Runner SR5 Auto -
4WD swapped
'89 Camry Alltrac LE 3S-GTE 5spd
'17 Chevy Volt Premier
'16 Honda Odyssey Elite
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