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  • #519172
    Jamie
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    • Chief
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    27th January 2019

    Evening all

    I recently had a CT and everything made sense with the exception of one ‘majeur’ error (which needs fixing within two months).

    This was, as per the report, “1.1.10.a.2 Dispositif de freinage assisté défectueux (Power-assisted braking device
    defective)”.

    My mechanic came over to look at the car and also read the report, but was stuck for what the problem could be.  To clarify, there are no problems with the brakes I am aware of.  He was also unsure how the test centre could have checked given it took all of 25 minutes and they don’t drive the car anywhere.

    However according to many numerous online guides (such as http://www.autoclubaix.com/fileadmin/documents/2017_CT/IT_VL_F1A-FREINAGE-090317.pdf, the criteria for this defect are:

    • Pour les dispositifs à dépression : absence de modification de la position de la pédale de frein constatée, au démarrage, lors du contrôle du fonctionnement ; Pour les dispositifs à haute pression
      hydraulique : voyant d’alerte du circuit hydraulique allumé, moteur tournant; Prise d’air.
    • For vacuum devices: no change in brake pedal position found when starting up, during function check; For high pressure devices: no change in brake pedal position found when starting up, during function check; For high pressure devices Hydraulics: Hydraulic warning light on, engine running; Air intake.

    In which case, none applies (I have tested the brake on engine start and there are no lights).

    Does anyone know if test centres literally just follow guides like these and will only look for the prescribed criteria?

    Will they look for other things too?

    Is there any way to know what’s wrong when all appears well?!

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    #519175
    Deboer
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    • Mega Star
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    Member since
    17th February 2019

    I would suggest returning to the test centre and asking them ? When the fault has been repaired , does the car need to be recontrolled ?

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    #519178
    John P
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    • Mega Star
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    Member since
    5th January 2017

    At the CT centre I use the test is always carried out in the same order and the results fed to a computer, but the mechanic also carries out a visual check and if he sees a problem this is fed into the system and printed out on the final document.

    What you have posted suggests some kind of problem with the servo unit. If you press your foot on the brake pedal with the engine running does it slowly creep towards the floor? If you can access the servo is there any signs of fluid leakage or is it showing signs of rust?

    That is the limit of my knowledge with modern vehicles I’m afraid.

    As Deboer says, if you can’t find the problem take the car back and ask the tester to explain. I have always found my local CT station to be helpful. Unlike the UK they are independant and have have nothing to gain by failing a vehicle.

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    #519182
    BartyB
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    20th March 2016

    All warning lights that should come on must come on when you switch the ignition on then go off when the engine starts (for instance: it stops you taking the bulb out of the ABS warning light rather than fixing the ABS)

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    #519184
    Fitter
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    • Super Star
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    Member since
    20th March 2016

    This is the standard way to test a vacuum brake servo:-

    To test for correct servo action, follow the instructions below:
    Test 1 Pump the brake pedal with the engine off until it becomes stiff
    and doesn’t travel.
    Test 2 Press the pedal with some pressure, start the engine and the
    pedal should travel as the vacuum should increase.
    Test 3 Disconnect the vacuum pipe. Connect to gauge to check for
    vacuum with engine running (min of 0.5 bar negative pressure). If there’s
    low or no vacuum, check the pipe, connections and pump (if it’s a diesel
    vehicle) and replace as required.
    Caution! On some diesel vehicles, if pressure is applied to the brake
    pedal for too long, the vacuum pump will build up enough energy and
    generate too much pressure in the brake system which can result in long
    pedal travel. This could make the driver think there is a problem.
    To be extra cautious, complete the steps as per Test 1. Then press and
    hold the brake pedal for a couple of minutes. If there is a leak in the
    hydraulics, the pedal travel will increase without servo assistance then
    follow the steps of Test 2.

    And the UK mot test for servo operation:- (The CT should be similar – but who knows?)

    Make sure the engine is switched off.
    Deplete the stored vacuum by repeatedly applying the service (foot pedal) brake.
    Fully apply the brake and hold at a constant pressure.
    Start the engine.
    Note if the pedal can be felt to travel further.

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    #519186
    Jamie
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    • Chief
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    Member since
    27th January 2019

    At the CT centre I use the test is always carried out in the same order and the results fed to a computer, but the mechanic also carries out a visual check and if he sees a problem this is fed into the system and printed out on the final document. What you have posted suggests some kind of problem with the servo unit. If you press your foot on the brake pedal with the engine running does it slowly creep towards the floor? If you can access the servo is there any signs of fluid leakage or is it showing signs of rust? That is the limit of my knowledge with modern vehicles I’m afraid. As Deboer says, if you can’t find the problem take the car back and ask the tester to explain. I have always found my local CT station to be helpful. Unlike the UK they are independant and have have nothing to gain by failing a vehicle.

     

    Hi- well I had a brief test this morning.   Tried the brake a few times with engine off and it was firm; started the engine and the pedal depressed smoothly until it stopped.

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    #519199
    Anonymous
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    • Mega Star
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    Member since
    1st January 1970

    My mechanic came over to look at the car and also read the report, but was stuck for what the problem could be.

    Get your mechanic to phone the CT station if you’re unsure of doing it yourself. Failing that, take it to a local garage where the chief mechanic will probably phone the CT station, that’s what happened with me recently.

    Just because you can’t find a problem doesn’t mean there isn’t one.

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    #519237
    Fruitcake
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    • Mega Star
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    13th July 2018

    One of the couple of ‘minor’ things our Clio has to be re-tested for is an oil leak, never seen any oil on the engine or under the car and the mechanic is going to have to pressure wash it to see if he can find it, apparently, it can be a danger to other road users it says in the small print.

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