Electric parking brake external application

[Kamil]

Hi Guys,

It might not be the best thread for this topic, but I'll write here anyway. I'm working on a project that requires a swap from manual, lever operated handbrake to an electric one. I've decided to use a Bosch unit that is used in several brands from PSA group. I bought a used unit from Peugeot 3008 MY12, but as I based my wirings on the electric diagram for Citroen C4 I believe those are the same modules.

The unit is connected to the a capable power source, a parking brake switch and to my canbus transceiver that I use to communicate with the module itself. I know that to manually release the brake you have to have a brake pedal pushed, so I've managed to find the canbus message that simulates this action and whenever I want to operate the handbrake I send it. After the message is sent I can operate the handbrake, but in quite specific way - if I pull the switch and keep pulling it the unit pulls the cable, but when I stop it retracts to it's default/open position. I thought this is some kind of learning procedure and I need to apply a pressure to the cable, so it knows when to stop. I tried that and the unit stops and retracts back, but I wouldn't call it a perfect simulation of a normal operating condition, so I can't say it's 100% not a case.

That's why I wanted to ask you guys, what this unit tries to do when I pull the switch. Why does it retracts every time? What conditions should it have to operate outside of the donor car.

[RichardW]

The unit might need a speed input? I think if you pull the switch when the car is moving then it only applies the brakes while the switch is held.

[GiveMeABreak]

You do realise that the ESP ECU controls the parking brake system - not just the ECU in the parking brake (master / slave relationship)? So if there is a problem with the ESP system, basic control of the system is handed back to the parking brake ECU.

So you would have to ensure you had a compatible ESP ECU and then that the BSI and ESP ECU was correctly configured. You also need to ensure that the dynamic breaking function works properly too, or you will have no emergency braking ability (for use by passenger if something happens to driver / or other failure).

[Kamil]

Yes, I'm aware of the ESP Ecu being part of the setup. However, for me it's just another complication that I would like to avoid. I would like to keep things as simple as possible. My goal is to completely mimic manual handbrake, but with EPB module and switch tandem. I'm expecting from the module only simple actions - pulling the cable on a pull of the switch when the brake is released and the other way around - releasing the cable on a pull of the switch when the brake is on.

Do you know if EPB can do those simple action without ESP ECU? I don't understand the behavior of the module I am experiencing now, which is pulling only when I'm holding the switch and getting back to default/open position when I release the button. Does it look like some adaptation or service mode?

I know this is very unlikely setup with the module operation outside of it's natural place, so I really appreciate your input. Thanks.

@Richard, thanks. Do you mean that the EPB will apply the breaks if you hold the switch and will keep them until you actually release it?

[GiveMeABreak]

I doubt it - it's managed as part of the software and dynamic stability programme controlled by the ESP ECU. Control is only handed back in an emergency - and is entirely controlled automatically.

Then there are all the CAN connections to all the various systems and the sensors that need to be considered.

This isn't something we are able to help with to be honest as what you are trying to do would have an impact on and will affect the vehicle safety systems.

[white exec]

Reading through the detail of this proposed brake modification, it does raise some serious concerns about dismantling and re-engineering part of the car's safety systems, with implications for driver and passenger safety, other road users, and certainly for roadworthiness and insurance.

It is something that the forum is not able to support, and would not wish to encourage others to get involved with.