EPB problem

[deakin6]

Hello hope someone can hello me?
2013 Citroen c4 grand Picasso mk1 1.6hdi. EPB is dead. Nothing works from brake button despite replacing it. Can activate and deactivate EPB from diagnostic tool without issue. Only code I have is C155A despite calibrating and tensioning cables. Anyone got pointers. I’m leaning towards EPB ECU.
Thanks

[GiveMeABreak]

As you can see it's likely to be internal to the EPB - the force sensor itself.

Fault Code:	C155A
Description of Fault:	Electrically-controlled parking brake not calibrated: Travel-effort pattern. Effort sensor not calibrated Conditions of activation of the diagnostics: Activation of the electrically-controlled parking brake.
Conditions for Fault to clear:	-
Downgrade Modes whilst Fault is active:	Deactivation of automatic mode No application or release Switching on of the warning lamp and/or warning message: Warning lamp - "a": lit - "b": On for 10 seconds after the request for application or release - "c": lit
Symptoms:	Illumination of LED/Error message Electrically-controlled parking brake does not apply correctly Electrically-controlled parking brake does not release correctly
Suspect Areas:	Force sensor (Internal electrically-controlled parking brake) Electric parking brake

[deakin6]

Thanks for reply. That being the case, I have a EPB ECU from a 2011 Peugeot 3008 1.6hdi. Are the modules the same? They look to be, just different part numbers obviously, one being pug and the other Citroen?

[GiveMeABreak]

I can't advise on that because these may look the same but if they have different part numbers, it's very likely they will be either mechanically different internally or have different software - which is important as the ESP ECU actually controls the EPB ECU as a slave. So they have to be able to talk to each other and perform the specific automatic functions of each vehicle - as again, they may have different features.

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[deakin6]

Update to my post. Changed EPB -ECU , tensioned and calibrated parking brake successfully via diagnostics, no change, exactly same as before, code C155A.
Anything else it could be? Thanks

[GiveMeABreak]

Why did you change the ECU? It's not that which is faulty according to the descriptor above - it's the Force Sensor...

[deakin6]

I thought the force sensor was integral to the park brake ECU? If that’s not the case, where is the force sensor please?
Have I misunderstood your reply when you said it’s likely to be internal to the EPB, the force sensor itself?

[GiveMeABreak]

I really need the VIN to see which system you have.

2013 was the changeover date to the B78, so need to confirm.

Please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff.

If it's like the others, there is usually a calibrated spring, magnet and hall effect sensor all integral to the unit, so realistically, you are likely talking replacement of the unit to be honest.

"m" Hall effect linear sensor.
"n" Calibrated spring.
"p" Magnet.
C Direction of movement of the magnet (Solid with the worm barrel ).
D Direction of movement of the worm.

The Hall effect linear sensor measures the stress force of the calibrated spring and the force transmitted to the barrel of the worm.

[deakin6]

Here is my vin. VF7**************[VIN obfuscated, can be read by forum staff]
When you say the unit , do you mean the EPB-ECU under the passenger seat, because that is what I’ve changed and calibrated and it brings same code C155A as it did prior to change

[GiveMeABreak]

Do you mean the complete assembly or components within it? That’s the entire handbrake unit. How do you know the replacement was also in good working order if that’s the case?

I don’t know what else to suggest as these are the only possibility suggested from the fault descriptor.

[deakin6]

The fact that it brings the exact same fault as before suggests that the fault lies elsewhere. Could it be cables or rear calipers, one of which was sticking and I freed off

[deakin6]

Also yes I replaced that complete unit under the seat rather than parts of it

[GiveMeABreak]

Well at least I've confirmed the model and the EPB is as per my picture.

See if a BSI Reset / Battery Disconnect / Reconnect Procedure will clear it after the ECUs are cleared and restarted. But you may want to leave it for a slightly longer period before the reconnection part and clear the fault code before doing this.

Nothing to lose.

[deakin6]

Thanks. I’ll give that a try and report back. What I can’t understand is how handbrake works fine via. commands from diagnostic tool but when I try from handbrake button, all I get is the flashing red parking light

[GiveMeABreak]

The diagnostic tool can directly perform actuator tests for the purpose of troubleshooting, so it's just asking the parking brake ECU to activate it. Unfortunately there's not much more I can suggest, short of checking manual EPB switch itself.