V70: Wheels/Brakes P3 Electric Parking/Hand Brake EPB Fault After Brake Service

[sae70]

Been a member for a number of years now. On my fourth V70 since joining, three P2's a T5 & two D5's and now a P3 2.0 D3. Do all my own servicing and maintenance when I can and I have to say that the Electric Hand Brake on this P3 has me considering the purchase of the best MY07 P2 I can find!!! Why has everything gone electric?! Even my Dip Stick has gone missing! Thank God it's still basically the same 5 cylinder diesel engine....

So rear pad and disc service, done the rear pads before using the same method had no troubles so wasn't expecting any issues this time round...

Put the EPB motors into the service position using a 12V leisure battery connected directly to the EPB motors after removing the normal supplies and tucking them up out of the way.

Removed the calipers from the discs and tucked out of the way, still connected to the flexi hoses.

Just about managed to remove the bolts for the caliper cages with heat and an undersized imperial socket hammered on due to corrosion of the heads.

Replaced discs and then had to wait a couple of days for new caliper cage bolt to arrive from Amazon...

If anyone's interested the caliper cage bolts are just High Tensile Steel (10.9) M12 x 30mm x 1.75mm pitch bolts, about £7 for six. The ones I bought have an 18mm head rather than a 15mm, but hey ho £20 saved...

While it was all apart I'd noted that the RH Caliper EPB motor was in a terrible state with the fixings all cracked and loose, so decided to replace the whole caliper, EPB motor and it's flexi with new ones. New caliper with EPB motor purchased from local MF and new flexi hose from Amazon.

All back together, brakes bled with Easy Bleed kit, saves having to communicate with the trouble and strife, down, hold, are you down or up, release, bla, bla ,bla....

Wheels still off, start engine, pump brakes, good pressure, EPB on, off, on, off etc....

LH caliper not coming on and remains fully wound out in the service position?! LH caliper not as messed up as the RH one so didn't replace it and works fine when wound in and out using the leisure battery and leads, so leave wound out (off) and get my son to come out and assist, again easier than the other available option unless you want an argument ;0)

Get my son to put the EPB on and off while I monitor each side. There's no action from the LH caliper motor either on or off not even a tiny short burst of action. Check with battery again and motor works fine so problem must be from electric input side. Found fuses left side of boot and both are OK and there's 12V on one side of each of the fuses holders when the fuses are removed.

Message on dash is that the 'Parking Brake is not fully Released', Parking Brake symbol is flashing and there's a Red Warning Triangle with an Explanation mark also flashing, OH and a pulsing BUZZER in case the rest of the warnings are not enough!

Anyway, needed to use the car the next day so made sure the EPB motor was fully wound off, left it unplugged and put the wheels back on.

Next day did a 70mile trip with all the flashing and BUZZING and had no issue as the LH EPB must be fully released as I'm doing 70mph up the M11 and I'm not on fire and getting 47mpg, despite all the BUZZING and flashing :0)

The BUZZING is starting to make me a little edgy though!!! Even on local trips...

So here I am a week later on a days A/L and I've had another go at it...

LH Caliper EPB motor winds in and out lovely with the leisure battery so I don't see a problem there...

I've checked the fuses again and they are both still fine...

I've tried to check for voltage coming from out of the plug, but couldn't see anything, should I be seeing something?

Disconnected the negative cable from the car battery for 30min to attempt to clear the fault as suggested by others, hasn't worked...

Help :0)

Anyone got a wiring schematic for the EPB system? And where's the EPB module?

Does anyone know why it would suddenly start ignoring the LH brake caliper?

Any help and input would be much appreciated :0)

Oh and if anyone knows where the BUZZING thing is please tell as I need to jam a screwdriver in it, thank you ;0)

[TeamG]

I’d concentrate on confirming whether there is any output from the LHS connector when applying/releasing the EPB handle with a multimeter. Try the RHS as a comparison. If nothing/unusual reading on the LHS then you’ve pinpointed the issue is not with the caliper motor (or not only with the caliper).

If identical readings to RHS, then you may have caused some damage to the motor with the leisure battery and for some reason it’s not registering properly with the car electronics. The EPB applies with 12V, but the current is monitored and as the brake force is applied, the current drawn increases to a set value when the car tells the motor to stop. The leisure battery will keep chucking 12V at the motor without stopping. I use a 9V PP3 battery for this reason as it hardly chucks out any current and cannot damage the motor.

[sae70]

It's an interesting point you make with regard the leisure battery and possible damage to the EPB motor as a result of 100Ah on tap, but I'm not Gun-Hoe with this operation and am reasonably confident that no damage has been done.

I'm also reasonably confident that there is no output from the LH side EPB connector which I did consider odd at the time, but latterly thought that this may be the case as the EPB module may have sensed that there was no motor connected and so cut the output to that side?

I'm on A/L again tomorrow so will implement your suggestion of comparing sides and may also make up a small wiring harness so I can measure the output of each connector while the EPB motor is plugged in.

May even extend the LH to the RH EPB motor as I know this one is working and see if this wakes up the LH output from the module. If this works then it may prove that I have damaged the motor with my Leisure Battery...

I hope it proves to be something so simple and within my skill set, fitting a new caliper, motor, flexi pipe and bleeding are all well within my skill set ;0)

It would be good to get a wiring schematic for the EPB system as the two 30Amp fuses were both permanently live that would suggest that the supplies then go on from there to the EPB module and then onto the EPB motors...

[SnineT]

All I can offer you is to check the wiring to the caliper and the pins inside the connector for breakages, other than that is it possible the new caliper isn't matched to the old one or even if that doesn't matter the car has sensed a new player onboard and won't let it activate until it's been told it's ok to be on the car?