Disco 3 (LR3) EPB Problem help required please.

terrykl · Jan 9, 2022

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?

marjon · Jan 9, 2022

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

terrykl · Jan 9, 2022

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.

marjon · Jan 9, 2022

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

marjon · Jan 9, 2022

Remembered this Other - EPB's | Page 3 | LandyZone - Land Rover Forum

Not the comment of the screeching even once freed off (albeit with the same old gears).

J

sierrafery · Jan 9, 2022

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

terrykl · Jan 9, 2022

marjon said:
Remembered this Other - EPB's | Page 3 | LandyZone - Land Rover Forum

Not the comment of the screeching even once freed off (albeit with the same old gears).

J

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.

terrykl · Jan 9, 2022

sierrafery said:
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

Thanks for this.

marjon · Jan 9, 2022

terrykl said:
Trying to operate the brake with the acuator cover off shows the motor trying to turn.
Stuttering while it screeches.
I have a wirring diagram.

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

terrykl · Jan 9, 2022

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..

terrykl · Jan 13, 2022

marjon said:
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

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?

gstuart · Jan 13, 2022

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

terrykl · Jan 13, 2022

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?

Picture above is with the brake engaged. Below released.

Nodge68 · Jan 14, 2022

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.

terrykl · Jan 15, 2022

Nodge68 said:
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.

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.

terrykl · Jan 15, 2022

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?

biketeacherdave · Jan 15, 2022

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.

sierrafery · Jan 16, 2022

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

terrykl · Jan 16, 2022

sierrafery said:
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

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.

terrykl · Jan 16, 2022

biketeacherdave said:
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.

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

Disco 3 (LR3) EPB Problem help required please.

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