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Service Brake soon

Discussion in 'Engine & Drivetrain' started by andrewjhunter1997, Apr 12, 2021.

  1. andrewjhunter1997

    andrewjhunter1997 Member

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    I had my Yukon xl for about 3 weeks and I keep having my service brake soon I heard that this could be a leaky brake booster or master any thoughts

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  2. Doubeleive

    Doubeleive Supporting Member

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    is it just the brake light or is abs lit up as well?
     
  3. Doubeleive

    Doubeleive Supporting Member

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    if it is just the brake light you could have low fluid, funky fluid level sensor (if equipped), or stuck proportioning valve.
    if the abs light is on also could be abs pump or air in the abs pump.
     
  4. andrewjhunter1997

    andrewjhunter1997 Member

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    Neither just as I'm driving the little screen comes up service brakes soon abs still work good and master is full pads on fronts and rears are like brand new

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  5. swathdiver

    swathdiver Full Access Member

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    You need a good scan tool or a bi-directional that can read chassis codes (ABS). With that you can pull any stored trouble codes and see how much pressure is in the system and whether or not it bleeds off as you press the pedal plus lots of other things.
     
  6. andrewjhunter1997

    andrewjhunter1997 Member

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    Well I did get something on my good scanner P0174 and P0101 but those just maybe stored from other vehicles

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  7. swathdiver

    swathdiver Full Access Member

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    Well, I would clear those and query the system again.
     
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  8. andrewjhunter1997

    andrewjhunter1997 Member

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    Just checked it again when I got home no codes

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  9. Doubeleive

    Doubeleive Supporting Member

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    the only reason "service brakes soon" comes on alone (no abs light) is if the fluid is low (or it thinks it is low i.e. faulty fluid level sensor) or the prop valve is stuck.
    in either case you won't have a code, your only indication will be with a advanced scanner such as a tech2 that can read the brake fluid level status
    as a test try unplugging the brake fluid level sensor, if the message goes away then it's likely the sensor unless you had brake work done lately and the prop valve got stuck in the process, in this case you can try bleeding the brakes slowly especially the rear. if there was no brake work done recently and the message is gone with the sensor unplugged then I would just replace the fluid sensor (easy fix)

    another thing to try if the prop valve is suspect (again only if work was done recently) is to drive and do several emergency stops, hit the brakes real hard, sometimes this unjams the prop valve.
     
    Last edited: Apr 13, 2021
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  10. andrewjhunter1997

    andrewjhunter1997 Member

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    Where's the senor plug out of curiosity?

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