C4 Picasso Electronic Parking Brake Adjustment?

[ChrisPembs]

Morning Everyone, would appreciate a bit of help, got a 2010 C4 Picasso, had it 18 months now, generally love it and so far been pretty stress free motoring, it has developed a problem on the drivers side rear wheel, last year it had new callipers, discs and pads all round, I noticed last week the driver side rear wheel calliper appeared to be sticking, have figured out over the last couple of days it is related to the parking brake, only stick if I apply the parking break, no sticking at all from the foot brake, it does release off after 10 minutes of driving and stays released unless I apply the parking brake.

Going to take the wheel off this afternoon and have a good look but was wondering if there are any adjustments that can be made to the cable? Feels like for whatever reason when releasing the parking brake it is not fully releasing on that wheel, if there is any adjustment where do you do it? At the calliper end or the motor end? Where even is the motor?

Any help appreciated and thanks in advance

[GiveMeABreak]

It depends on the system you have fitted. Pop your VIN up so I can see what you have. On early C4 Picassos, they had an electric handbrake unit that operated on the rear brake cables connected to the calipers.

When you had the work done I assume that the parking brake was put into the service position first and then afterwards it is essential to calibrate the electric handbrake (re-defining of the handbrake application starting point). This is done with a Lexia or other professional level and capable diagnostic tool.

[ChrisPembs]

Morning Marc Thanks for the reply I appreciate it, VIN is VF7**************[VIN obfuscated, can be read by forum staff] all the work was carried out by what I would perceive as being a competent garage nearly 12 months ago now so "assuming" they did it the correct way but sadly have no way of knowing that for sure, as all I can say it is has worked with zero issues for almost 12 months until last week.

[GiveMeABreak]

Ok, so you have the EPB assembly that operates on rear brake cables as I mentioned.

(1) Automatic electronic parking brake.
(2) Electric parking brake rear right secondary cable.
(3) Electric parking brake rear left secondary cable.
(4) Electric parking brake primary cable.
(5) Electric parking brake manual unlocking control.

As the parking brake seems to be operating and you have no warning messages, I think we can exclude the actual EPB itself and the primary cable (4).

It may be the rear right caliper sticking, the rear right caliper cable (2), or may be able to be corrected using the calibration procedure again.

[ChrisPembs]

Marc thanks so much for the diagrams that is really helpful Guessing there is no manual adjustment on the cables and it is all computer controlled? As mentioned there is not sticking at all using the footbrake so guessing any sticking will be from the lever on the top of the calliper that connect to the handbrake cable? Will get the wheel off over the next couple of hours and have a good look, see if I can see what is going on.

If everything appears free and I can find someone with a Lexia or indeed buy one, been meaning to for ages now, can it be recalibrated with half used pads or would I need to replace the pads first?

Thanks

[GiveMeABreak]

You are correct, as there is no sticking with footbrake application it has to be cable / calibration related as far as I can see.

Yes, the procedure is in replacement parts section of Lexia. There are 2 operations:

Operations to be carried out following the replacement of a parking brake cable

Carry out the handbrake cables packing procedure:

• Select the menu:
• Replacement Parts
• Replacement of the brake cables
• Packing of the cables

Carry out the electric parking brake calibration procedure:

• Select the menu:
• Replacement Parts
• Replacement of the brake cables
• Calibration of the electric parking brake

[ChrisPembs]

Thank you, I suppose it could be a simple brake cable fault, next step, get the wheel off! Will update this later in case anyone else has similar issue and once again, thank you

[GiveMeABreak]

Just don't attempt top remove the handbrake cables unless you have a lexia, as the EPB has to be put into service mode to slacken the cables sufficiently.

[RichardW]

Not on a MK 1 Marc, as long as the brake is off, the cables are released. One of the cables pulls the outer, if it's a bit snagged it might not release.

[GiveMeABreak]

Just quoting here for work on the caliper Richard as this was what was originally replaced when he had the work done, but worth a mention as it relates to unclipping of the cables on the caliper:

When operating on a rear brake caliper, it is essential to use a diagnostic tool in order to:

• Place the electric handbrake in the removal position (provides the clearance necessary for unclipping of the cables)
• Tamp down the cables after each repair on a rear brake caliper
• Calibrate the electric handbrake (re-defining of the handbrake application starting point)

[ChrisPembs]

Ok quick update, took the wheel off and it turns out the handbrake mechanism on the calliper was really really sticky, only half releasing so attacked it with a generous bath of WD40 and a wire brush, after gently persuading it with a hammer to fully release and then applying and releasing the parking brake 10ish times it is back to working as expected now, not sure how long it will last, must be road salt, mud etc seeping into the joints, will monitor and see how it goes, made a right mess of the new disc I put on last year though, not overly grooved but the heat has damaged the surface sadly, pads have about a quarter material left on them so will use as is for a few weeks and put new new pads both sides and a new disc on the one side that is now no longer brand new Will also fully replace the 11 month old calliper if it sticks again, I do a decent amount of mileage around 25k a year so need to to work as it should really.

Hope that helps someone and thank you for your help today, appreciate it