C5 III X7, fail of manual brake-function

[XMClive]

Hello,

I try to turn to this forum, because my C5 III X7 (2014 HDI Excl.) has a very special problem, maybe someone can help;
in the German forum there’s nearly nobody, who has similar trouble.
Code ‘C1555’ (only), manual brake-switching doesn’t work, automatic on/off is working as it should, P-Symbol displayed permanently, nothing else.
Already done:
Battery renewed, all fuses checked and cleaned, wires so far as possible checked, manual-switch renewed, brake-unit renewed (!, >1000 Euro).
Result: Still the same trouble. Since I don't have access to a wiring diagram I can't get any further now.
Is there anyone who knows more about the wiring, respectively how to go on ?

Thanks,
Clive

[wheeler]

What is your VIN & i can see if i have the wiring diagram available?

[XMClive]

Hello Wheeler,

VIN is VF7**************[VIN obfuscated, can be read by forum staff]

Thanks in advance !

[wheeler]

Hi, got the VIN but wont be able to check for a diagram till i get home later tonight.

[XMClive]

No problem;
Thanks a lot for your effort !

[GiveMeABreak]

I've tidied up this thread and deleted the non-relevant posts.

This is the fault code. Diagram to Follow:

Fault Code:	C1555
Description of Fault:	Activation/deactivation control fault of the electrically-controlled parking brake : Short circuit to positive or short circuit to earth. Short circuit to positive. Short-circuit to earth or wire broken. Lines in short-circuit. Signal not coherent. Fault occurs on presses of the activation button.
Conditions for Fault to clear:	Disappearance of the push button fault.
Downgrade Modes whilst Fault is active:	No manual application or release. Switching on of the warning lamp and/or warning message Warning lamp: - "a" : lit - "b" : Not on - "c" : Not on
Symptoms:	Illumination of LED/Error message Electrically-controlled parking brake does not apply correctly Electrically-controlled parking brake releases unexpectedly Electrically-controlled parking brake does not release correctly Electrically-controlled parking brake applies itself unexpectedly
Suspect Areas:	Push-button electrically-controlled parking brake Electric parking brake

7092: electric handbrake / control
7095: electric handbrake assembly /

[XMClive]

Thanks a lot, GiveMeABreak !
My DIAGRA also showed the comment
'Activation/deactivation control fault of the electrically-controlled parking brake : Short circuit to positive or short circuit to earth.',
your code-explanation is more detailed.
So contacts 4,5,9,10 of the brake switch(es) are just connected directly with the black brake-unit at the rear axle
(= 7095/'electric handbrake assembly' ?) - is this correct ? Unfortunately I wasn't an A-pupil in English-lessons ...

[XMClive]

assembly=Baugruppe,
understood

[wheeler]

So contacts 4,5,9,10 of the brake switch(es) are just connected directly with the black brake-unit at the rear axle
(= 7095/'electric handbrake assembly' ?) - is this correct ? Unfortunately I wasn't an A-pupil in English-lessons ...

Correct.

It looks like pins 1,2 & 3 are only for the LED lamps inside the switch although pin 1 of the switch shares an earth connection with pin 2 of the handbrake control unit.

[XMClive]

Since the LEDs are working it just could be broken/bitten wires 4430..4433 or their contact to car-body.
Earth and Voltage are not needed for switch-signals, as far as I see.
Furthermore there is no hidden relais or socket/plug to check, good news.
I have to remove the covers from the underbody to check the harness a bit more; I will report about results.
Thank you very much !

[Suomipoika]

It was a C5 (2015) fault with manual braking 7092: electric handbrake / steering / 7095: electric handbrake assembly / wire 10 across the protective tube. About 10 cm from the connector to the electrical assembly. Wire 4430.