Pins 4 & 7 for stereo

Hi everyone how do I swap over pins 4 & 7 for an after market stereo or where can I get this done cheap as I'm useless at this kinda stuff

Hello Mikecoop82.

In the wiring harness that came with your new radio there will be a yellow and a red lead. They should have 'bullet' connectors on. You unplug these and swap the wires round so red goes to yellow and vica versa.

If you haven't already got one, you'll need another wiring harness to convert the Citroen wiring to ISO connectors so you can plug your new radios wiring into the car.

Don't be surprised if you get some odd behaviour, if you leave the radio on so it goes on and off with the ignition, it might go off a couple of minutes after you turn the ignition off and also come on when you unlock the car.

Alternatively instead of using a wiring harness that converts the Citroen wiring to ISO, you can fit one with an electronic box that will generate a true ignition signal so the radio behaves conventionally. This type of converter allows you to keep steering/stalk audio controls and trip computer functions if you have these now.

Brilliant thanks a lot for the reply I can plug the existing connectors straight into the new radio but had the same problems with remote locking as others have

I have (had) the same issue.
Symptoms were:
- central locking would not respond after cca. 15min
- radio would continue playing for few minutes after I removed the key
- radio would start playing when I unlocked the vehicle

I resolved the issue with unpluging of the radio so I am quite sure it is the 4-7 pin thing. The ISO connector enables quick swap of 4-7 pin. Before I make the 4-7 pin switch I would like to make sure that it is safe. I red that there are some digital pins that are connected directly to the ECU/BSI and if the wiring is not completly correct one can fry the thing. As I've been reading pin 4 and 7 are both +12V (analog for that matter) so in theory no digital signal should be transmited on them. Can anyone confirm that? Which are the digital com. pins? Can I swap the 4-7 pins?

Thanks

The problem with swapping out the factory radio is that there is no ignition live on the Citroen radio connector. It has a permanent live and something I call'VAN live'. VAN is the digital signal used by the car to control many of its functions, it's an 'in-house' Peugeot/Citroen system which was a predecessor to CAN, now used widely on many if not all cars.

The 'VAN live' is not a digital signal, it switches on when the car is unlocked and off a few minutes after the car is locked and the system goes into sleep mode.

You can get two sorts of wiring harness to get around the ignition signal.

1) An ISO adaptor which has a fly-lead for ignition live, 90% plug and play, just the fly-lead to connect to a switched ignition source, eg the cigarette lighter.

2) An electronic ISO adaptor which is fully plug and play. It will generate all the signals your radio needs from the car's digital data bus (VAN). This type of adaptor can also allow you to continue to use any steering wheel or stalk audio controls if you have them and the new radio has a remote control input.

Thanks , my C3 doesn't have the steering wheel commands.
So what you are saying is:
There is Citroen permanent live which directly corresponds to ISO A4 (12V from battery) but is located on pin A7
There is Citroen "VAN live" which roughly corresponds to "ignition on/off" ISO A7 pin but is located on pin A4

So I can switch pins 4-7 and just live with erratic behaviour of "VAN live" as opposed to true ignition on/off behaviour? I am not looking for true ignition on/off functionality, "VAN live" erraticness is acceptable. Also I do not use any plug-n-play functions.

My only worry is not to fry the ECU/BSI as I red somewhere that somebody replaced the radio, connected it and then everything went dark. If I am not mistaken he had to pay few hundred quid for replacing the computers and everything.

ISO pin diagram used: https://pinoutsguide.com/CarAudio/car_au ... nout.shtml

Thank you for your time

jakasi2 wrote:So I can switch pins 4-7 and just live with erratic behaviour of "VAN live" as opposed to true ignition on/off behaviour? I am not looking for true ignition on/off functionality, "VAN live" erraticness is acceptable. Also I do not use any plug-n-play functions

This will work, but be careful about drawing way too much current with some very powerful head unit. If you want to draw lots of power, then you wouldn't want to swap the wires over, but rather do a proper independent power install.

jakasi2 wrote:My only worry is not to fry the ECU/BSI as I red somewhere that somebody replaced the radio, connected it and then everything went dark. If I am not mistaken he had to pay few hundred quid for replacing the computers and everything.

This is possible if you 1) get the wires wrong and end up NOT swapping 4 and 7. You should put a multimeter on the wires you intend to swap to ensure they are actually what you think they are (12v and 12v switched by the computer).

2) If you draw way too much current, I would imagine frying the BSI is a real possibility. The system wasn't designed to run very powerful head units, and it was never designed to have 4 and 7 swapped, but can cope with this situation if its not abused. The BSI delivers the power for 4 and 7, so any mistakes will damage the BSI.

Thank you for the reply

I am quite sure they are the ISO compliant power/ignition wires since the car has "central locking" symptoms and the manual of the radio unit also says that the wires are used for this + I am using the harness that came with the unit itself.

If I would like true ignition on/off functionality which adapter harness should I buy? Also if I decide install the adapter should I reswap the 4-7 pins?

jakasi2 wrote:If I would like true ignition on/off functionality which adapter harness should I buy? Also if I decide install the adapter should I reswap the 4-7 pins?

If you have an adaptor with the red and yellow leads that can be disconnected (as mentioned above), use this and connect one to the battery via fuse and one to the 'accessory' position in the ignition switch (or some other suitable point), also via a fuse. There will not be a 4 and 7 to swap over because they will now be connected to the battery and some other place. Obviously the 4 and 7 supplied by the car will not be used and can be safely insulated.

jakasi2 wrote: I am using the harness that came with the unit itself.

Unless the adaptor is designed for the C3, it won't work correctly with the C3.

Thank you for the reply . I swaped the pins, soldered the wires and installed the stereo. It works like a charm.
My setup is really simple: radio (Pioneer DEH-2700UI) and 2 speakers, nothing to power hungry so I think BSI power/current supply should endure it.

Also I quite like the erraticness of "VAN live". When I unlock the car my favourite radio station is already playing


One thing I noticed is that when the stereo was disconnected the car would lock itself 1-2min after i left it. After installation I did not notice that behaviour.

I attach the pic of soldered pins
One more time.. thank you for your answers you were all very supportive.