C-ABS : DTC 5-1 fault code

Discussion in 'Maintenance' started by kensou, Nov 27, 2019.

  1. kensou

    kensou New Member

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    Hi !

    Getting flashing ABS yellow light... error code is 5-1.

    meaning according the Honda manual :
    Front power unit malfunctionl / air bleeding incompletion

    is my front power unit blown ? due to the heat of the exhaust (using my blade to go to work, a lot of traffic..)

    is there a way to test that the front power unit is fine ?

    Would like to be ensured that the front power unit is OK before processing the full ABS bleed.

    note : when i reset everything by disconnecting the battery, the light is off, but when i attempt to brake with the front lever, i feel like a very small depression at the lever, as if there was a hole in the brake fluid line, then the yellow light starts flashing.
    but front & read braking stay efficient, and the front brake lever does not touch the throttle grip if i pull it hardly.

    thanks for your help.

    Kensou
     
    #1 kensou, Nov 27, 2019
    Last edited: Nov 27, 2019
  2. derchef

    derchef Well-Known Member

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    you are not resetting , just with a battery disconnection.
    When was the last brake fluid flush?
     
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  3. kensou

    kensou New Member

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    I don't know really...
    being that the previous and first owner had respected fully the maintenance schedule @honda, i suppose that the last brake fluid flush has been done on time (if it's well planned on the maintenance schedule). The color of the brake fluid seems fine (clear orange)

    I had tried also to reset the error code with the Honda procedure (CLEARING DTC @ page 17-9).
    but the yellow light flashed immediatly, when rolling.

    With the disconnected battery, it was off, when rolling, but at the 1st medium front braking, the yellow light flashes
     
    #3 kensou, Nov 27, 2019
    Last edited: Nov 27, 2019
  4. Slick

    Slick Senior Member

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    Braking feels fine once the ABS light is flashing because you are now running in failsafe ie the ABS is not active.

    Got this error tried everything, multiple bleeds, new ecu, new modulator, heat protection on front power unit and nothing worked.
    In the end just disconnected the ABS.
     
  5. kensou

    kensou New Member

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    So it's a good new to know that normal braking is working even if yellow light is flashing
    However, i d like to make working this C-ABS :D
    Thanks for your reply
     
  6. Slick

    Slick Senior Member

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    The front power unit replacement could be a pricey fix, it may involve removing the radiator and I think potentially the headers.

    I also commute in heavy traffic, strangely the fault came up around the same point in my journey. Lever would feel wooden then ABS would go into failsafe.

    Bleeds on their own are generally temporary fixes, a hard lever in failsafe would suggest there is no air in the system in the first place.
    You can still do a conventional bleed easily, I would do this first with a good clean of the callipers and disc bobbins before you start spending
     
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  7. kensou

    kensou New Member

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    You're right, thanks for your feedback.

    but what i forgot to say, is that now, when the motorcycle starts to roll, the light is flashing immediatly.
    before it was flashing after a long moment in a big traffic.
    the fact that the light is flashing now immediatly, let me think that this power unit module is failed... but i hope i'm wrong
    that's why i wanted to know whether there is way to test this front power unit (moreover, DTC returned is 5-1).
    if this failure can be confirmed, i would prefer do brake fluid bleeding 1 time, with a new front power unit (saw good price on ebay).

    Do you know where i can get the procedure for the CONVENTIONAL procedure ?
    it's just bleeding through the nipper of the front caliper and adding brake fluid in the reservoir ?

    I'm strongly convinced that this problem is due to the heat of the exhaust.

    So, i planned to :
    install thermic band on the exhaust manifold
    install heat shield covering the front power unit
    use a brake fluid with the best high point of boilure (greater than the conventional one)
    and why not an extra fan (like a fan for radiator) to cool the module

    what do you think about that ?
     
    #7 kensou, Nov 30, 2019
    Last edited: Nov 30, 2019
  8. Slick

    Slick Senior Member

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    I used a heat shield on the unit and racing fluid, but the issue still manifested. I cant really see even normal fluid boiling in this scenario as a reason, I do think it more likely to be mechanical.

    Unfortunately the diagnostics in the front unit is just simply to replace, if the issue is resolved then the unit was faulty.

    Sometimes the issue can be caused by excessive travel of the pistons ie the pistons retracting causing the ECU to record low pressure. This could be caused by dirty corroded pistons, gummed up seals so a good clean may help. However, if the light starts flashing even before you apply the brakes it does indicate a total failure when the ECU does its start up diagnostics.

    A conventional bleed is just a normal bleed via the master, furthest caliper, nearest caliper then master again, just make sure this is done with ignition off and do not let the reservoir go empty, a world of pain will follow if you allow air in the system. If you want to do a DIY ABS bleed they are simple enough if are mechanically minded though the front unit is a pig to reach.


    I would also suggest pulling the ABS fuse whilst you resolve, the ABS going into failsafe whist in traffic is bum squirming
     
    #8 Slick, Nov 30, 2019
    Last edited: Nov 30, 2019
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  9. kensou

    kensou New Member

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    Thanks for your precious reply :!!!


    I just called a Honda dealer in Paris a few minutes ago, they told me that a wrong brake fluid cannot make flashing the ABS light.
    ABS light = problem with a module.
    Are they right ?

    * i also add : when i try to disconnect & reconnect the battery, the light goes off, when rolling !
    but when i try to pull the front lever, it starts flashing !
     
  10. Slick

    Slick Senior Member

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    As long as you're using DOT4 you wont be causing issues.
    The issues do point to the unit but as would give the calipers a good clean and flush the fluid first.

    Also something to try, erase the error code and ride to over 30mph without applying the front brakes, (use the rears only if you must but gently), it may may reset the fault - obviously do this only in a safe controlled environment!!!!!!!!!
     
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  11. kensou

    kensou New Member

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    Thank a lot man !
    now just cleared the DTC, and disconnected the battery.
    i will proceed flush + cleaning calipers tomorrow. + your TIP :)

    Keep you informed tomorrow night

    have a nice day
     
    #11 kensou, Nov 30, 2019
    Last edited: Dec 1, 2019
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  12. kensou

    kensou New Member

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    Hi Slick !

    Gonna try to clean the pistons of the front brake calipers right now.

    Just one basic question :

    will i need to take the piston out fully and collect the flowing brake fluid ?
    if yes, air can go inside the brake line ?

    or will I just need to take them out at 70% ?

    Thx
     
  13. Slick

    Slick Senior Member

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    No need to take pistons out, you are only bleeding/flushing. Definitely don’t want to let air in the lines
     
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  14. kensou

    kensou New Member

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    Dear SLICK,

    Thank you so much : IT WORKED !

    Here is the sequence of all actions i did, including your recommendations :

    * Cleared the DTC error
    * Disconnected the battery since yesterday night
    * Cleaned the 2 front calipers pistons (find attached a photo taken during the operation) by using a tooth brush and water+soap.
    * Bleeded the front brake fluid (the old one was darker than the new one)
    * As liquid were remaining, i bleeded also the rear brake fluid (the old one was darker than the new one)
    * I did not see where was the nipple of the master cylinder so i didn't do it.

    * I tested ride the blade without applying the front brake for 10 mn, above 30km/h, only using rear brake.
    after a 10 mn ride , i started to use the front & rear brake, gradually, by hoping the ABS light doesn't come :)
    IT DIDNT COME.
    at the end of the test ride, i squeezed hardly the front & rear brakes, STILL OK.

    So, i don't know which action exactly solved the issue (probably the brake fluid replacement), but all these actions solved the problem.
    So it meant that the ABS ECU was enable to detect something wrong with the brake fluid ! (where as the Honda dealer told me yesterday that an ABS light must be a faulty part)

    I hope it will not come back soon.
    So, i will expect that the abs light will flash again, but if it's in 1 year, it's ok for me, as now, i know how to proceed, and this operation is quite simply actually (watched so many youtube tutorial videos lol).

    last question : you told to bleed also the master cylinder but i did not see the valvve.
    where is it exactly ? i would like to bleed it next week end

    SLICK --> THANK YOU AGAIN !!!!!! you make me save costly parts replacement ! even if that this issue will occur again :(

    PS : Please, send me a PM with your home address, i d like to offer you a good french bottle of red wine, if you like wine
     

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    #14 kensou, Dec 1, 2019
    Last edited: Dec 2, 2019 at 12:11 AM
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  15. Slick

    Slick Senior Member

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    You're very welcome, though I love good wine there's no need for your kind gift just glad it helped!!

    If I had an error I would normally ride to 30mph without using the brakes to reset the fault, however most of the time it was not possible to do so.
    I didn't normally have to clear the DTC or disconnect the battery though.
    I think some fault just get stuck in memory and this procedure just allows the ECU to pass the diagnostic checks

    I do hope with the cleaning and bleeding you have resolved the issue but do ride cautiously until you are confident the ABS is behaving itself.

    FYI I dont think the rear master has a bleed nipple, some crack open the banjo but I dont think this necessary as the fluid exits from the top so any air will reach the rear caliper nipple.
     
    #15 Slick, Dec 2, 2019 at 10:14 AM
    Last edited: Dec 2, 2019 at 11:44 AM
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  16. kensou

    kensou New Member

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    Thanks for your advice.

    You told me that the front master could be bleeded, i did not process it because i did not find the bleed valve.
    is there a bleed valve somewhere ?

    Also i think, 'not sure', but i think air went into the rear brake line.
    Because i felt yesterday night, during the ride test, that's a little bit spongy, needed to press hard the rear brake lever to brake normally, and when i was bleeding the rear fluid, i had seen some small air bubble going out...
    Do you think i can remove all bubbles if i continue to bleed through the rear nibble ?

    Many Thanks for your support
     
  17. Slick

    Slick Senior Member

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    upload_2019-12-2_17-11-28.png

    The front master nipple is located as indicated.

    The rear does not have a master, you can either crack open the banjo (but I dont like this as you should also replace the washers).
    My preferred method is to raise the rear wheel as high as you can and bleed from the rear caliper.

    One other tip is zip tie the lever over night, this helps in a few ways, resets the seals, compresses any bubbles so it helps air to rise to the bleed nipples,

    I wrote up a convention bleed procedure which I will forward, also another member wrote up a ABS procedure if you feel brave to try
     
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  18. Slick

    Slick Senior Member

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  19. Slick

    Slick Senior Member

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    this is probably when the CABS activates the front unit when using the rear pedal
     
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  20. kensou

    kensou New Member

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    you are GOLD !
     
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