Brake lights in spite of changed BSI - need advice

[uhurusurfa]

Hi All
I have read all the posts on brake lights in the forum and tried all the proposed solutions I can find but no luck getting them working so far.

I have:

• Verified the left and right brake light bulbs are functional
  
• Removed the tail gate brake light bulb (top of the tail gate) as it was blown ... not sure if there has to be a working brake light bulb here for the rest to work but imagine not as that would be a fauilt INtolerant system
  
• Verified that the brake switch under the dash correctly has 12V on pin 2 which is connected through to pin 1 and registers 12V on the outgoing wire from pin 1 when brakes are pressed
  
• Removed the brake light switch and turned car on attempting to verify reports that the BSI should turn brake lights on by default if the switch is NOT connected - the brake lights do not come on
  
• Removed the BSI, acquired a (supposedly) fully functional replacement BSI and had the existing software cloned to the replacement BSI. Exactly the same behaviour is exhibited as for the original BSI (ie no working brake lights)
  

Given that all 3 lights do not work (I have verified that there is no voltage provided to the tailgate light when brake is pressed using a multimeter) and the brake lights do not come on by default with the switch removed I am reticent to rule out the BSI at this point.

I tried figuring out where wiring goes using the diagrams provided in this post: https://www.berlingoforum.com/thread-25639.html
The wiring diagram seems to be different as mine uses pin 2 on the switch for receiving 12V from the fuse in the engine compartment (verified by removing the fuse in the engine compartment) and pin 1 feeds 12V out when brake pressed but the wire seems to go back into the engine compartment instead of to the BSI.

However, I have been unable to figure out the entry pin to the BSI from the brake switch but given removing the switch does not default the lights to ON I am assuming the problem is either in the BSI or in a short on the wiring from BSI to brake lights.

I have also not been able to identify the exit pins on the BSI that should provide power to the brake lights (when brakes pressed) so that I can verify if there is a voltage being provided and therefore the problem lies in the wiring from BSI to back brake lights.

At this point I am wondering if there is anyone that can provide advice on any further things I can do to isolate the problem like perhaps providing some hints on how to identify the pins on the BSI.
Is there a way to have the BSI tested in isolation to prove that the brake lights are activated in the BSI?
I have some photos to provide context

   

   

[brodfather11]

The brake light switch om my 2012 B9 is under the passenger side dash , it has a connection to the clutch pedal switch , ( it has cruise control ). The diagram you refer to does not show the cruise control connections . The switches are different for cruise and non cruise  types.

Saying that is the wiring between the tailgate and body intact , with the tailgate opening and shutting the wires get twisted and moved every time it is opened and closed. Unusual if all 3 wires were broken and only the brake ones.

The diagram shows a component between the fuse and brake switch , don't know what that is for ,  a dimmer if the main h/lights are on to stop the brake lights dazzling drivers behind  perhaps ?

Would a scan show fault codes ?

[Multispacer]

Hi All
I have read all the posts on brake lights in the forum and tried all the proposed solutions I can find but no luck getting them working so far.

I have:

• Verified the left and right brake light bulbs are functional
  
• Removed the tail gate brake light bulb (top of the tail gate) as it was blown ... not sure if there has to be a working brake light bulb here for the rest to work but imagine not as that would be a fauilt INtolerant system
  
• Verified that the brake switch under the dash correctly has 12V on pin 2 which is connected through to pin 1 and registers 12V on the outgoing wire from pin 1 when brakes are pressed
  
• Removed the brake light switch and turned car on attempting to verify reports that the BSI should turn brake lights on by default if the switch is NOT connected - the brake lights do not come on
  
• Removed the BSI, acquired a (supposedly) fully functional replacement BSI and had the existing software cloned to the replacement BSI. Exactly the same behaviour is exhibited as for the original BSI (ie no working brake lights)
  

Given that all 3 lights do not work (I have verified that there is no voltage provided to the tailgate light when brake is pressed using a multimeter) and the brake lights do not come on by default with the switch removed I am reticent to rule out the BSI at this point.

I tried figuring out where wiring goes using the diagrams provided in this post: https://www.berlingoforum.com/thread-25639.html
The wiring diagram seems to be different as mine uses pin 2 on the switch for receiving 12V from the fuse in the engine compartment (verified by removing the fuse in the engine compartment) and pin 1 feeds 12V out when brake pressed but the wire seems to go back into the engine compartment instead of to the BSI.

However, I have been unable to figure out the entry pin to the BSI from the brake switch but given removing the switch does not default the lights to ON I am assuming the problem is either in the BSI or in a short on the wiring from BSI to brake lights.

I have also not been able to identify the exit pins on the BSI that should provide power to the brake lights (when brakes pressed) so that I can verify if there is a voltage being provided and therefore the problem lies in the wiring from BSI to back brake lights.

At this point I am wondering if there is anyone that can provide advice on any further things I can do to isolate the problem like perhaps providing some hints on how to identify the pins on the BSI.
Is there a way to have the BSI tested in isolation to prove that the brake lights are activated in the BSI?
I have some photos to provide context

Have you checked the engine bay fuse box for any sign of water/liquid damage? A number of Citroen models including the Berlingo are known to be prone to problems from water damage of this box, which is not only a fuse box but has a circuit board that operates some functions in conjunction with the BSI. The most common cause of water damage of this box is rain water from the scuttle panel area that flows onto/into the box if leaves block up the scuttle drains. 

In my case, it was not rain water but a rodent had got inside the box and used it as a toilet with the liquid causing all sorts of weird problems including the rear wash/wipe suddenly not working and a number of STOP warnings randomly appearing on the dash with the weirdest fault being the wipers and headlamps randomly switching on with the car stopped and ignition off!!

[uhurusurfa]

@brodfather11 - No cruise control on mine so those 2 wires are only used to detect hte presence of the brake switch in the BSI (since it is supposed to be connected between pins 3 and 4 by default)

@Multispacer - the power to the aswitxh is fine so the compnent between fuse and switch if it exists must be working I am hoping someone on the forum can answer the question of what a scan would show