Forum Discussion

mikemc53's avatar
mikemc53
Explorer II
Mar 09, 2019

electric brake booster

I have a 2004 HR Vacationer (Ford V-10) that has an electric brake assist system. The brake booster motor runs constantly with the key in the on position and I was wondering where to look to fix this. My guess is that it would only need to run when the brakes are applied but it seems to run all the time.

I bought the vehicle last summer and it has always done this - I have just ignored it because I really didn't know what it was until the other day. When turning the key to "on" before starting I would hear it but, normally, couldn't hear it after start due to the engine noise. Well I wanted to do a 5 Star tune on the coach and leaving the key "on" was really loud without the engine running - also I think this booster is keeping the 5 Star from working because I am not getting vehicle info nor is it connecting (error message 110B8). I would like to fix the booster issue for a couple of reasons, not the least of which is the fact that a constantly running motor is not necessarily a good thing.

Thoughts?
Class A
  • DrewE's avatar
    DrewE
    Explorer II
    Mar 11, 2019
    tragusa3 wrote:
    Sorry. I hear the hydroboost buzz when I put the key to the on position. Once I start the engine and while driving, I do not hear the buzz.


    That sounds like proper operation to me, based on what I remember of how the system works (which may not be quite precisely right). There's no need for the electric back-up booster pump to run when the engine is running and the power steering pump is pumping.
  • 10forty2's avatar
    10forty2
    Explorer
    Mar 11, 2019
    tragusa3 wrote:
    Sorry. I hear the hydroboost buzz when I put the key to the on position. Once I start the engine and while driving, I do not hear the buzz.


    Seems to be the way it works....our 1999 HR does it too! When the key is on, but engine not cranked...as in when deploying stabilizers...the annoying buzzing is there. When key is not turned, no buzz unless you press on the brake pedal. When cranked, it makes no noise at all. Had brakes system bled 3 years ago when I replaced the brake lines and calipers....buzzed before and after, so I gotta guess it's the way it's designed to work.
  • tragusa3's avatar
    tragusa3
    Explorer
    Mar 11, 2019
    Sorry. I hear the hydroboost buzz when I put the key to the on position. Once I start the engine and while driving, I do not hear the buzz.
  • wolfe10's avatar
    wolfe10
    Explorer
    Mar 11, 2019
    tragusa3 wrote:
    Following. Our "new to us" coach has always done the same. I'd never owned one before and assumed it was normal. Braking seems to work fine.


    Sorry, not clear on what you mean.

    Does your hydroboost work all the time the ignition is on (OP's coach) or only when you press the brake pedal?
  • tragusa3's avatar
    tragusa3
    Explorer
    Mar 11, 2019
    Following. Our "new to us" coach has always done the same. I'd never owned one before and assumed it was normal. Braking seems to work fine.
  • Robert_F_K's avatar
    Robert_F_K
    Explorer
    Mar 11, 2019
    I have a good manuel with trouble shooting. Is there a way to attach the file here
    Bob
  • PastorCharlie's avatar
    PastorCharlie
    Explorer
    Mar 09, 2019
    I have the hydro boost brake system and the electric motor only runs when the brake pedal is pressed.
  • DrewE's avatar
    DrewE
    Explorer II
    Mar 09, 2019
    I think these use hydroboost brakes, with the electric backup for the main power steering pump. It sounds as though the pressure from the power steering pump is not making it to the brake system for some reason; if the power steering seems to be operating normally, I might guess (and it's purely a guess) that there's a problem with the valve system for the hydroboost brake accumulator...or perhaps a bad switch to turn the auxiliary pump on and off.

    At first glance it would not appear to be related to the five star tune problem, but I don't totally discount that possibility. Vehicle systems are not always obvious in their interactions and failures!

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