Brake Light possibly caused by dieing vacumm pump

Today on my way to work i glanced up into my review mirror. i saw out of the corner of my eye a red light pop up on my dash. i looked and it was my red brake light. by the time i looked down and saw what it was it went out and never came back. my stopping power never really changed, but the firmness of my brake pedal increased a little bit. i am sure some of you remember all the brake problems i was haveing a few months ago. my pedal has always been soft, but the braking power was never in question. today when the light came on the pedal feel became what a normal pedal would feel like. i drove for a couple more miles and stoped at a stop sign and stop light and then my "normal" pedal feel and brake power came back. it was fine the rest of the way into work with no light coming back. everything was fine coming home as well. i checked my MC fluid level and it was right up there.

I don't know of any vacumm pump history on my truck but does my symptom sound like a dieing vac pump? is there anyway to tell if the original vac pump is still on the truck?

When i had my truck in school my teacher hooked up a vac tester and said it pulled 25 inches at idle and held steady.

Another thing....When i am coming to a stop if i hit the brakes the pedal is soft with decent stoping power. if i let off and hit it again right away the pedal gets firmer by quite a bit and the brakeing power goes away by a noticable amount. if i keep pumping the pedal it gets harder and harder and brakeing power goes down and down. if i wait a few seconds between pumps then everything is "normal'.

Thank in advance.

That does kinda sound as though the pump may be getting weak and takes time to build the vacuum back up so that you get the assist from the booster.

Fordsandguns said:

That does kinda sound as though the pump may be getting weak and takes time to build the vacuum back up so that you get the assist from the booster.

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That's kind of what i was thinking.

I have been following this thread over on FTE. seems as though me and the OP have the same issue.

http://www.ford-trucks.com/forums/1087230-vacuum-question.html

I had a vac pump go out suddenly one night. I slowed for the turn onto my street and then for the turn into the drive just fine, but when I hit the pedal in the drive it was hard as a rock. I have a f250 parts truck sitting there and it was coming up fast! Both feet on the brake stopped me in time. Thank goodness I don't fly into the drive like some people I've seen.
Another night I had the alternator belt come loose and took out the others. The power steering belt was still on but twisted and cut.
It is scary stopping one of these things without the power assist on the brakes.

Fordsandguns said:

It is scary stopping one of these things without the power assist on the brakes.

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I bet. all the momentum these heavy truck gather up makes them a bear to stop.

Your brake light is actuated by the emergency/parking brake. You had a little better braking because the E/P brake may have been on partially. If that helped with braking then your rear drum brakes need adjusting up. Easy to check your vacuum again and see if it has depleted any from the 25 inches your school instructor registered.

OLDBULL8 said:

Your brake light is actuated by the emergency/parking brake. You had a little better braking because the E/P brake may have been on partially. If that helped with braking then your rear drum brakes need adjusting up. Easy to check your vacuum again and see if it has depleted any from the 25 inches your school instructor registered.

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I thought the red brake light will come on if any number of things are wrong including low vacumm. i checked my parking brake and it was released all the way.

It could be like what happend to me at 2:30 am today - my light came on so I "tapped" the brakes to see if it was gonna hit the floor or be stiff as can be.....well it was the later of the two. At this point I proceeded to pull over and verify the vacuum line was hooked to the booster, the manifold (vacuum) and the pump itself.....

Well the hoses were all intact and located in their proper respected locations so I then started the truck up to notice my vacuum pump pulley was not rotating! Great.

Since I was literally in the middle of nowhere I limped it back to my buddies house to look at it in the light and have a few beers to calm my misery - about 2 hours go by and I start the truck and the pump was no longer locked up....weird. I then passed out on the couch and when I was going to leave early this afternoon, it was still working, well, for a while anyways.

About 10 minutes in to my ride home, the light proceeded to come back on and once again, the pump was locked.

After this entire ordeal I presume there ought to be some sort of bearing assembly that is locking up on the pump? I don't really know.

Thankfully I have a spare on the shelf, but no vacuum is a scary ordeal.....I am ready to hydroboost after this incident.

brdmh44 said:

It could be like what happend to me at 2:30 am today - my light came on so I "tapped" the brakes to see if it was gonna hit the floor or be stiff as can be.....well it was the later of the two. At this point I proceeded to pull over and verify the vacuum line was hooked to the booster, the manifold (vacuum) and the pump itself.....

Well the hoses were all intact and located in their proper respected locations so I then started the truck up to notice my vacuum pump pulley was not rotating! Great.

Since I was literally in the middle of nowhere I limped it back to my buddies house to look at it in the light and have a few beers to calm my misery - about 2 hours go by and I start the truck and the pump was no longer locked up....weird. I then passed out on the couch and when I was going to leave early this afternoon, it was still working, well, for a while anyways.

About 10 minutes in to my ride home, the light proceeded to come back on and once again, the pump was locked.

After this entire ordeal I presume there ought to be some sort of bearing assembly that is locking up on the pump? I don't really know.

Thankfully I have a spare on the shelf, but no vacuum is a scary ordeal.....I am ready to hydroboost after this incident.

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Glad to hear you made it home in good shape.

Glad to hear you made it home in good shape.

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THANKS!

Sadly, this was minor compared to a brake failure that occured on my 94 extended cab 2wd..... I was pulling a 20 ft trailer with a sub compact tractor on the back when my left front brake rotor sheared in half during an emergency stop instance thanks to someone pulling out in front of me while approaching a red light.

I was slowing down and bam, my pedal goes right to the floor....at this point all I could do was look for a safe escape route to not harm myself or others....Thankfully I hopped the curb and passed the vehicles in front of me on a grass parkway.

Now that was a scary ride with a load behind me! If it wasn't for my emergency brakes and trailer brakes both being in working order, it could have ended up being a tragedy. I cannot emphasis enough when it comes to safe towing and driving!

While this was a fluke incident with the rotor shearing, it was not something to take lightly...after this incident, a full brake overhaul was performed with the best parts possible.

Stay safe everyone!

Well it happened again today coming home from work. i was driving through town and my red brake lite came on. it stayed on for ~30 seconds. the really odd thing was that when it decided to turn off it did not just go out, the lite slowly faded out until you could not see it. then a few miles farther down the road the lite came back on and was on for about 10 sec then went right out, it didn't fad this time. All the while i was driving with the lite out and with the lite on my brake pedal and braking power was the same as it allways is.

I don't have any brake fluid leaks, my parking brake of completely disengaged. the only two things i think it can be are the vacumm pump or the power booster. my reasoning is i have read some threads on other forums and when their vac pump was going out their pedal behaved the same mine does. also the fact that those are the only two items left that i have not replaced.

I will do some searching on here for some more info. any body have a good recomendation on a vac tester to test my system and start crossing things off the list?

My money is on the pump NOT the booster. I was also thinking the low vacuum switch may be the culprit. I have the exact same problem and same light situation. My brakes are hydroboost, hence no booster. I would like to find the cause of this light issue too!

Well I changed the vacuum pump and realized it most likely failed due to a faulty belt tensioner..

bghnkinf350 said:

I have the exact same problem and same light situation. My brakes are hydroboost, hence no booster. I would like to find the cause of this light issue too!

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If you converted to hydroboost from vacuum, The vacuum sensor may still be hooked up. The sensor is not plugged in on the F-450's. Just unplug it and the light should go out.

'94IDITurbo7.3 said:

Well it happened again today coming home from work. i was driving through town and my red brake lite came on. it stayed on for ~30 seconds. the really odd thing was that when it decided to turn off it did not just go out, the lite slowly faded out until you could not see it. then a few miles farther down the road the lite came back on and was on for about 10 sec then went right out, it didn't fad this time. All the while i was driving with the lite out and with the lite on my brake pedal and braking power was the same as it allways is.

I don't have any brake fluid leaks, my parking brake of completely disengaged. the only two things i think it can be are the vacumm pump or the power booster. my reasoning is i have read some threads on other forums and when their vac pump was going out their pedal behaved the same mine does. also the fact that those are the only two items left that i have not replaced.

I will do some searching on here for some more info. any body have a good recomendation on a vac tester to test my system and start crossing things off the list?

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Change the pump. It WILL fail at this point.