Parking brake light stays on

[Slicknik]

I second the test redneck says.
Sounds like your booster is failing

- If it took more than a minute to get to 23 psi you have a weak pump.
- Another test to run is how long your system holds vacuum after you turn the engine off.

 

[mf7lakes]

When I put the vacuum gauge on the brake booster hose, 1) the vacuum pressure from the vacuum pump showed up immediately at 23 -- 2) as soon as I shut the engine down, the gauge went to zero

I did start & stop the engine twice to check

Now that booster source does go through the vacuum manifold then up to where I crammed in the connector to my test gauge -- who knows how air tight all that could be?

Mitivac hand vacuum tester/pump

 

[Cant Write]

Following along as I’ll have to tackle this down the road.

I’m leaning towards failing booster with mine.

 

[mf7lakes]

Soooo, I think the slicknik is correct -- pulled off check valve and tried to blow through it -- nuttin' honey -- worked as advertised

Next, put brake to the floor with engine running, then turned engine off, still holding pedal to the floor --- pedal pushed back at me (did it three times to make sure)

I'm told that's a sure sign of failing/failed booster

Tell me something, please guys --- and thanks

 

[Rdnck84_03]

I'm told that's a sure sign of failing/failed booster

I don't have any input on that. All of the ones I have had to replace would have the whoosh under the dash followed by a hard pedal.

James

 

[Slicknik]

You need to watch the gauge as you pump the brakes and see if it drops (while the truck is running), buy some vacuum plugs at autozone and start plugging the manifold and isolate the one that’s leaking. If it’s the vacuum line to the booster then you found your problem

 

[mf7lakes]

Well, here's where we are ---- from the vacuum manifold to the vacuum low pressure switch (on drivers side wheel well almost under the battery) is a 1/4 id hose -- I wiggled it -- the hose immediately separated from the lo psi switch -- part of it was inside the hose in pieces -- well, I think I've found the cause for the BRAKE light -- the switch itself and now it ain't got no plastic nipple anymo.

so plugged that hose and pryed off the elec connector -- no BRAKE light -- and I still have brakes and they act just fine -- guess I'll get a vacuum gauge to monitor as I can't find that exact low pressure switch anywhere
(E3TA-12A182-AA)

 

[Rdnck84_03]

Shouldn't need the exact same design as long as the amount of vacuum required is close to the same. But honestly I think the gauge would be better. I think ford should have used a separate light for low vacuum.

James