C5 x7 handbrake mot fail

[GiveMeABreak]

I've just read through the removal and fitting procedure of the EPB unit and it seems pretty straight forward, with no fancy measuring procedures etc. I appreciate that you are not contemplating removal at this point John, but all the adjustment seems to be with using Diagbox to put the system into 'removal' mode if you were going to replace the unit and more importantly, when a replacement has been fitted, to apply the calibration routine using the same afterwards.

By all accounts the EPB systems seem quite reliable, so when you have your calipers back on, do you think it would be beneficial to perform the calibration routine even though it hasn't been replaced?

I suppose we should be grateful we don't have the VW / Audi, Mercedes systems, as they opted for the system with actual motors and reduction gears inside the calipers themselves! These are then subject to the usual water ingress and braking component stresses which have been causing premature failure in many cases. The system used by PSA is also used by BMW, GM & Ford / Jag.

[jgra1]

Hi Marc.. we still haven't worked out how to disable handbrake using diagbox I disable now using the manual override

Can you hazard a guess at the calibration.. what actually.happens and how do I instigate it

[GiveMeABreak]

John - just did a quick edit on previous post - Give me a second and i'll see if I can pull anything out of the proverbial hat.

[jgra1]

Ahh great ..thanks Marc.. yes i was going to pretend I had replaced unit later today to see what that will achieve.. fingers crossed..

Edit..

What procedure I wonder..
pump brakes.vac bleed brakes .. then recalibrate or
Pump brakes vac bleed brakes then start car and handbrake as normal then recalibrate..
Or
Something else..

[GiveMeABreak]

John - I couldn't find a written procedure anywhere - but I have managed to locate a video with a guy doing this on his 508 - will be the same I'm sure - just pause the screens to see where he's at and read the info as he is a bit quick and it doesn't help he hasn't got the camera straight - but looks like he is in the:

• REPAIR menu
• then test by ECU
• then selecting SECONDARY ELECTRIC BRAKE
• then REPAIR
• then PACK REPAIR
• REPLACEMENT PARTS
• ELECTRONIC PARKING BRAKE REPLACEMENT

Then you will get the 3 options - PUT IN FITTING / REMOVAL POSITION, CABLE TENSIONING and ELECTRIC PARKING BRAKE CALIBRATION.
He does reverse back through it after if you get lost! But I think this is where you need to be - even to check for any faults etc. Let us know if this helps.

[jgra1]

Ahh great Marc !
Tension or calibrate .. I will look later and see how I get on

[GiveMeABreak]

I would suggest tension first as it 'sounds' like it could mean it will adjust the cables which is what you want really - we don't really know here as none of us have any idea of what is involved - so it sounds like the least drastic!

[jgra1]

well not too much news..
I bled as best as I could on my own with the vac unit.. but it wasn't too impressive..
then I plugged in and went straight to pack replace and straight to calibrate.. (I think I read somewhere on a Jag forum that was right)

and the handbrake operated itself several times and that was that..
I then checked for binding.. nothing.. and operated the handbrake manually a few times including extreme mode.. still no binding..
I rebled the brakes using a one way valve but with engine off.. did some more parameters and noted a few numbers..
I did get a parking brake error at some point.. but cleared those 3 ok..

so .. I am not 100% the brakes are bled properly yet.. which may or may not affect the handbrake power.. the wheels are on and no binding of any note..
I think tomorrow I will either get some help with bleeding (with engine on?) and may even recalibrate again, check for binding and then see if I can test if either wheel will hold car on a slight slope , one at a time.. then I may try and drive her to local garage for a brake test on Sat am.. and then on to the mot at noon for a full retest..

dunno..

[GiveMeABreak]

John - seems there are 2 issues here - brake bleeding and the handbrake issue.
Logical to get the brakes working first, as all the handbrake will do is operate the calipers and if they are not working anyway then the rest is not going to make any difference. Do you need the brake bleeding procedure or do you have that?

With the brakes working, the handbrake (remember should be in release / fitting mode via Diagbox before doing any work on the rear brakes as it will engage again when you turn the engine back on / off) will need to be reactivated using Diagbox, and the 'tension' option I'm guessing first of all before calibrating.

This brake bleeding seems to be a right pain in the ar*e.

[jgra1]

Hi Marc issue was.. mot fail on offside handbrake. Only..

Between the test and the retest I had replaced pads and discs at back without bleeding

retest almost passed handbrake (it would have scraped through) but

nearside caliper was binding ..caused during the retest for handbrake

.. my concerns are that the brakes don't bind ever again as it ledt me quite stranded..

and the offside handbrake will stop car on its own.. I.e. it's a lockup ..
I don't really understand why the nearside caliper bound ..
I have replaced both calipers with used units

Erm

Now both brakes don't bind.. and I may try a third bleed the old fashioned way..with help.. and hopefully something somewhere has helped the offside handbrake get through a full mot

Grr

Many thanks for all your support so far! You're a massive credit to this forum.

This poor white X7 will carry on with a new mot very soon in am not massively concerned about the functioning handbrake failing the mot .just a bit annoyed that it works really well compared to many vehicles I have had.. luckily I have somewhere to work on it and spare things to get to work on/in..
But ..for anyone ..if you have a car that you know well..has plenty of spares and support.. and does a perfect job for you ..don't rush to upgrade ! As a wise forum member once told me

[GiveMeABreak]

John, thanks for that, just want to help you get past this issue in any small way, as I can just sense the frustration over this episode!

At least we have all got a better understanding now of what to look out for.

[jgra1]

she's through.. I have a wadworths 6x ..job done..

mostly unsatisfying really.. she still didn't look too good for the EPB test, but in the end full application was requested .. then the rollers tried to undo that.. 250kgs both sides..
What have I learnt.. pads and discs are easy to change.. calipers too..
the newtons of force within Diagbox are the key.. I think 1000+ for normal application, and 16-1700 for full handbrake.
the calibration (I did it twice) didn't obviously improve the normal application value (mine was more like 500N)
the handbrake works very well when car is switched off, but the MOT doesn't really test for that it seems..
I never tried the 'tensioning' part of the Diagbox session.. I may do this at some point to see what it does..

thanks for all help.. I am off to Oxford in the X7 to help brother with bathroom work

John

[GiveMeABreak]

Ok - great, thanks for the udpate John, let us know what is in that other menu if you get round to trying the tensioning option later. You can chill now for another 12 months!

[civvie]

This question is for John as he has had the tee shirt and done it. Or anyone else who can help.

It refers to the electric hand brake, last year I was informed that my hand brake had only just scrapped through the test, now the test is on its way again in August and I'm trying to cover any problems. John I remember in your posts on replacing pads etc on the back you said you turned off the brake in PP, replaced the disc and pads then re-initialised the hand brake.
I'm thinking if I could do the same on my car IE reset the parking brake it may give the system a bit more bite for the MOT, any comments on this? If positive I might bite the bullet and talk to Easydiagnostic

[jgra1]

Hi steve.. replacing my discs and pads didn't help my handbrake. It was worth a try and they were shot anyway..
Overriding the handbrake didn't help (switching off manually).. but your need to do this to change pads etc.

I think I did a calibration in diagbox .. this didn't help either..

The only thing lest is a handbrake tensioning in diagbox.. I will do this soon but it means testing handbrake at a garage afterwards.. this is the crux of the problem with the epb ..you can't really tell if you have fixed it without the rollers..

However.. there is a measurement in diagbox that gives overall force and this is useful ..

For my mot I made the garage test the handbrake with engine off.. as that is full application and it passed..
Sorry a bit of a ramble