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Disco 3 (LR3) EPB Problem help required please.

Discussion in 'Land Rover Discovery' started by terrykl, Jan 9, 2022.

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  1. terrykl

    terrykl Member

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    I have a 2008 Discovery 3 which apart from the three amigos has given me no problems for five years, until now.
    I had the screeching EPB problem and brake jammed on. I pulled the emergency release, stripped out the rear brake system, fitted new gears in acuator and all new cables, shoes calipers and pads. Reset the DCT codes. The acuator made a different screeching sound and didn't apply brake. The DCT registered 'Emergency release had been pulled', yet it had not and the latch in the acuator between the two cables was still connected..
    I have had the acuator working correctly, out of the vehicle by attaching the motor direct to a battery.
    How does the DCT know the emergency release has been pulled, is there a sensor somewhere?
    Is there any way of testing the electrical side of the EPB within the vehicle?
    Any ideas?
     
  2. marjon

    marjon Well-Known Member Full Member

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    I would guess the D3 uses the same logic as the L322.
    Yes it will know according to the fault code list.
    If the emergency has been pulled it takes 2 activations of the handbrake switch after, the first pull should relatch it all.

    Have you done the bed in procedure and correctly adjusted everything?
    What diagnostics are you using?

    J
     

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  3. terrykl

    terrykl Member

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    I have checked the re-latch and it is attached.
    I have adjusted everything as procedure.
    I'm using icarsoft diagnostics.
    I have not done bedding in as all youtube demos show the EHB working normally before they bed in.
     
  4. marjon

    marjon Well-Known Member Full Member

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    I wonder if its the force sensor in the box, could it have been overpulled the first time and failed. but that would show a fault code, so probably not that.

    I can give you the wiring for the L322 if it would help any?
    You replaced the gears is there a specific orientation I wonder?
    If its still screeching then it must be trying to apply can you tell if there is any movement at the cables.

    J
     
  5. marjon

    marjon Well-Known Member Full Member

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  6. sierrafery

    sierrafery Well-Known Member

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    Hi, i dont have much experience with this but see how the system works and what's the possible cause and action for the fault code you get. Good luck
     

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  7. terrykl

    terrykl Member

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    Trying to operate the brake with the acuator cover off shows the motor trying to turn.
    Stuttering while it screeches.
    I have a wiring diagram.
     
    Last edited: Jan 10, 2022
  8. terrykl

    terrykl Member

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    Thanks for this.
     
  9. marjon

    marjon Well-Known Member Full Member

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    Got any pics of what you are seeing.
    As you bench tested and it was fine, is it the extra load now that is showing issue with motor/mechanism?

    J
     
  10. terrykl

    terrykl Member

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    Yes it's when its trying to apply. Its trying to turn the but i can't tell if its the mechanical that's jammed or the motor not delivering enough power..
     
  11. terrykl

    terrykl Member

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    Took the front cover off the acuator to see what was happening when switch was pulled up. The motor was trying to turn to release the cables which where already in the released position. Cleared the error codes and switched the motor connections over ie. blue to top, red at bottom. Pulled up switch and the motor pulled the cables as normal to park position. Pushed the switch down nothing happened. Reversed the motor wiring, pulled up switch and the motor released the cables. Any ideas how I fix this problem?
     
    marjon likes this.
  12. gstuart

    gstuart D3 Grandad

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    Hi

    wires should be red on top, blue underneath, assume u rewound it after pulling the release

    here’s a thread that goes into detail, if the shoes arnt adjusted correctly indeed the force sensor sees how much force is being applied when the switch is applied , if the force is to great the force sensor will tell the EPB to release the shoes as there’s too much tension on the cables

    here’s the link, plus can I take some pictures please with the cover off so we can see where the relevant assembly parts are plse , thks

    brake guide

    https://media.disco3.co.uk/gallery/albums/userpics/11748/Bodsys_Brake_Bible_V1_6a_CompressPics.pdf

    guide to show u where the threaded rod should be

    https://www.disco3.co.uk/forum/epb-repairunjam-relatch-91299.html?highlight=epb

    hope that also helps
     
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  13. terrykl

    terrykl Member

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    The threaded rod was turned in five times as guides. I cant get a total picture of acuator due to lack of room.
    Not sure where cable tension would be as I followed Bodys guide and wheels turn, though stiffly. Attaching a battery direct to motor operates the engage or release with no problem.
    The white box on the left on mine seems to be further out than those in the links you gave?
    Part Engaged.JPG
    Picture above is with the brake engaged. Below released.
    Released.jpg
     
    Last edited: Jan 13, 2022
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  14. Nodge68

    Nodge68 Well-Known Member

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    How did you power the EPB module, with it out of the vehicle? The module uses a data signal via the CAN bus, which is pretty impossible to replicate out of the vehicle.
     
  15. terrykl

    terrykl Member

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    I only powered it direct to the motor terminals to ensure the newly fitted gear cogs function as they should. They did. I also did the same when the unit was in the vehicle and brakes assembled. Again attaching a battery direct to motor and it operated the engage and release with no problem.
     
  16. terrykl

    terrykl Member

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    My problem persists so I tried.

    1. Cleared fault codes.

    2. Removed 30amp fuse.

    3. Disconnected actuator motor red & blue wires.

    4. Wired actuator motor direct to spare battery.

    5. Powered the actuator motor to engage and disengage brakes (no problem).

    6. Left the actuator motor slightly wound in with the outer end of the threaded rod about 30mm in.

    7. Disconnected temporary wiring from actuator motor and replaced red & blue wires.

    8. Replaced 30amp fuse.

    9. Pulled hand brake up switch.

    Result was.

    Actuator motor turn did not turn to engage the brakes but turned the other way to disengaged and continue to do so for 4 seconds.

    Code C1A5368 Manual emergency release activated - automatic parking brake actuator module cable reengagement (latching) failed.

    Yet it is still connected.

    Any ideas?
     
  17. biketeacherdave

    biketeacherdave Well-Known Member

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    Does the icarsoft dia have an unlatch function ??. I'm only asking as my id tool does and when I replaced my handbrake shoes and serviced the mechanism I had to use this function to reconnect the cable.
     
  18. sierrafery

    sierrafery Well-Known Member

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    I attached you docs in post nr 6, did you actually read them? Cos i see you insisted to power that actuator out of the vehicle while in the description doc it's clearely stated that :
    Prior to removing a brake disc from a vehicle, power should be disconnected from the parking brake module.
    Operation of the parking brake switch while a brake disc is removed can cause the actuating mechanism in the
    parking brake module to seize.

    so IMO powering that module without being completely attached is not a good ideea

    also in the diagnostics doc you have a clear procedure for that C1A3568 fault code and despite of what videos are on youtube the bedding procedure is compulsory for the system to work well
     

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  19. terrykl

    terrykl Member

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    Thank you for this I will read the docs again. My actions 1 to 9 were with everything installed in the vehicle including brake assemblies. Does not the actuator need to be able to engage the parking brake before you can start the bedding in procedure? At present the actuator just goes into release mode when I pull up the switch.
     
  20. terrykl

    terrykl Member

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    No I only have the iCarsoft Multi-system Scanner i930.
     
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