Testing a vacuum pump
Senior User
Joined: Jan 2011
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Wow holy dead thread but icame across this searching for the fix to what seems to be the exact same problem... I'm on my 2nd reman from the parts store and now the symptoms you were describing is happening to me. Is this vacuum switch onthe booster and where did you get a replacement?
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
The switch/sensor that activates the light is on a separate vacuum line, near the vacuum distribution box. From either the vacuum pump or the brake booster, follow the vacuum line. They both lead to the distro box (IIRC it's also called the vacuum "manifold"). That box has four lines - one to the vac pump, one to the brake booster, one to the HVAC and one to that sensor/switch. The sensor is fairly near the distro box, like less than a foot away, driver's side under the hood. So just follow each line coming from the distro box; you'll find one that goes to a roundish thing with an electrical connector on it. That's the sensor (switch, what have you).
Senior User
Joined: Jan 2011
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ok i found the sensor/switch, now how do i proceed to test if its good or not? Do i just unplug the electrical connection? And what should happen? I just want to make sure the switch is the issue bec ford is the only one that sells it and for 98$...
Senior User
Joined: Jan 2011
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I can't hardly push the pedal down! haha and its a similar feeling to what it was like when my first vaccum pump went out. Then i replaced it with one from oreillys and it literally tore itself apart within 3 months... Then i replaced it again and i havent had any issues until the other morning. But yes the light is going on and off when im trying to push the pedal down. I just dont wanna have to replace the pump if i dont have to again
Lead Driver
Joined: Mar 2006
Posts: 5,098
Likes: 1,504
From: western SD
Get a vacuume gauge and check how much the pump is pulling. You can check the vacuume atfrom the hose that runs to the brake booster. A minimum of 19 inches should be there. That switch only controls the light in the dash.
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Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
^^^^^+1; if the pedal is hard and the light is going on, then the sensor and light are working RIGHT; it's telling you that you don't have sufficient vacuum to run the booster. So the pump is once again a prime suspect. I have no direct experience with the FLAPS vacuum pumps (usually Cardone), but from reading the forums, they seem to have a reputation for not lasting long. Cardone reman parts are somewhat known for their less than stellar longevity. Turns out it's cheaper to offer a "lifetime warranty", and count on most people not bothering with it, and send another blown-out part down to Mexico (taking an American job with it) to be reman-ed for next to nothing, than it would be to build in some quality in the first place.
I've only had to replace one vacuum pump; found one at accuratediesel.com that's NEW, and they claim is OEM, only a few dollars more than the FLAPS crap. 30,000 miles / five years later it's going strong.
I've only had to replace one vacuum pump; found one at accuratediesel.com that's NEW, and they claim is OEM, only a few dollars more than the FLAPS crap. 30,000 miles / five years later it's going strong.
Senior User
Joined: Jan 2011
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So here's a couple intresting things today... I went to start the truck and it worked like it should! It drove perfect except the ABS light came on for a couple miles and then turned off when I parked the truck. When I was on my way home there was no ABS light, but when I was halfway through a turn, the truck died???!!!! Flipped it in park, started her up and ride the rest of the way home perfect! I'm so clueless right now guys about my brake problem and does anyone think the truck dieing is related? Bec it happened once before a couple months ago pulling outa the drive... But it was before I had any brake issues!
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