2007 C5 MK2 remote control assembly

[sydo]

Hello everyone, I have a 2007 C5 and I can't get a spare remote for the original one. I've been to many locksmiths, but the remote opening and closing function doesn't work. The immobilizer is programmed, the car starts, but the remote control doesn't work. As a solution, I bought an external remote opening and closing module and I'm going to install it. Should I take the trigger cable for the opening and closing function from the driver's door trigger or the BSI opening and closing trigger? Also, which trigger cables are these? I'm waiting for your help.

[mickthemaverick]

I have moved your post to the Citroen section as your problem is not really relevant to the diagnostics section and you have a better chance of some help here. Good luck

[sydo]

I have moved your post to the Citroen section as your problem is not really relevant to the diagnostics section and you have a better chance of some help here. Good luck

Thanks, but there's no one who can help yet.

[mickthemaverick]

You have to be patient and see what happens. Some members only come on the forum once or twice a week so it's a matter of waiting for the roght one to login.

[Huskyxantia]

For your 2007 Citroën C5, installing an aftermarket remote central locking module is a practical workaround when the factory remote frequency cannot be paired.
​1. Where should you take the trigger from? (Driver’s Door vs. BSI)
​It is highly recommended to intercept the trigger signals at the BSI (under the dashboard/grommet area inside the cabin) rather than running new wires directly into the driver's door shell.
​The Multiplexing Issue: Your 2007 C5 uses a highly integrated CAN-bus multiplex system. The BSI manages the central locking digitally.
​The Door Boot Risk: Routing external wires through the flexible rubber boot (grommet) between the pillar and the door is incredibly tedious and prone to future wire shearing due to the door opening and closing.
​The Smart Choice: It is much easier to locate the harness inside the driver's footwell or kick panel where the wires exit the door loom and head toward the BSI, and tap into them there.
​2. Identifying the Cables in Your Photo
​The 6-pin plug you photographed connects directly to the door lock actuator mechanism. Because PSA (Peugeot-Citroën) identifies wires by text numbers printed directly on the insulation rather than relying strictly on standard color coding, colors can sometimes shift slightly depending on the exact factory batch. However, the standard layout for this specific 6-pin plug typically follows this structure:
​Green/Yellow: This is universally Ground (Earth / -) on all PSA vehicles.
​Lock/Unlock Motor Power (2 Wires): Typically two of the thicker wires (often the blue/white or orange variations). These swap polarity (+12\text{V} and Ground) momentarily when the BSI tells the door to physically lock or unlock.
​Microswitch Switches (3 Wires): These lines tell the BSI the state of the door (Door Open/Closed) and if a physical key is being turned in the door barrel (Lock/Unlock command).
​3. How to Wire the Aftermarket Module Safely
​The cleanest way to wire an aftermarket remote module into a multiplexed Citroën without throwing error codes or frying the BSI is to configure your module for a Negative Trigger System (sending a brief Ground/Negative pulse to simulate a physical key turning in the lock cylinder).
​To find exactly which wires on your harness are the correct triggers, use a digital multimeter or a 12V test light:
​Step-by-Step Testing:
​Securely connect your multimeter's negative probe to the Green/Yellow (Ground) wire or a bare metal chassis point.
​Back-probe one of the remaining thin wires with your positive lead.
​Test the Lock Trigger: Use your physical mechanical key blade in the driver's door lock and turn it to the Lock position. The wire that momentarily drops to 0\text{V} (or grounds out) when you turn the key is your factory Lock Signal.
​Test the Unlock Trigger: Repeat the process, turning the mechanical key to the Unlock position. The wire that responds by grounding out is your factory Unlock Signal.
​Once identified, configure your aftermarket module's output harness for a Negative Trigger layout (usually involves tying the module’s internal relay "Common" wires to Ground) and splice its Lock and Unlock signal outputs directly into those two factory lines.

[sydo]

Which BSI socket can be used for the trigger cable for switching on and off? BSI has many cable sockets.