C5 x7 parking brake help

[citroenxm]

I had a visit from an owner of a c5 x7 with faulty parking brake.

The parking brake motor isn't making any sounds, however lexia claims to calibrate it correctly when I try and calibrate it. I've told the car its had cable work... however im second man in... this is the story.

The nearside caliper locked up tight. A plastic sleeve had broke so the cable passed through and I guess the motor compensatated by over winding. The owner managed to manually free it with the release under the arm rest and cables are all connected back up..

Under calibration theres some clicks and thuds under the car and diagbox says calibration done however theres no noise from the motor.

Interestingly though... and roll back works on it as long as the steering wheel isn't touched first. For example if we stop the car.. switch off... then switch on the anti roll back works. However once the steering is turned it won't work...

My first question is ... does the parking use a different motor to the anti roll back applocation..?

Were complimating swapping the parking unit for another to get it all working

[GiveMeABreak]

The anti roll back on these is operated by the parking brake system on the rear wheels (it doesn't have calliper motors as you probably know) , controlled by the ESP ECU. The ESP ECU is the master ECU and controls the slave ECU in the EPB. As everything relies on everything else as usual, any fault in the ESP system will inhibit various functions, including Hill start assist. It really depends on what the fault codes are.

If you have any of these, put them up here Paul. I suspect the touching of the steering wheel has triggered the Steering Wheel Angle Sensor which is also part of the ESP system, so it may be doing some checks and then deactivating Hill start again.

[citroenxm]

Dam I didnt think of recording the fault codes. As we had almost decided to swap the unit out for another one. .

[citroenxm]

Yea I could see the calipers are completely mechanical..and the hill start isn't directly mounted which is why I asked if there 2 separate motors in the parking brake black box.

[RichardW]

Pretty sure hill hold is independent of the park brake and just uses the hydraulic service brake held on by the ABS block....