2014 strange electrical issues

[Verl123]

Hi all

I have a 2014 diesel berlingo. Today I noticed the brake lights weren’t working. Tested the brake switch and that was fine. Had 12V present at the tail light plug, but then found on both lamp holders a break in the circuit? I then bridged the break on each lamp holder and the brake lights worked again. Surely this isn’t a coincidence? What on earth would cause that?

As if that wasn’t strange enough, I noticed the top lamp in the tail light has two filaments. I figure one of these is also a brake light combined with a tail light but not sure (can someone confirm?). The second filament wasn’t activating when I pushed the brake, so I thought I’d replace the globes with these https://www.supercheapauto.com.au/p/endu...3D&start=1

At this point in time the bottom lamps were working when I pressed the brakes. The lamps up top were only working as parkers, nothing happening when I pressed the brake. I changed both globes, then the bottom brake lights would work for a second then not work at all? I then changed back to the original globes and the bottom brake lamps came good.

It didn’t stop there, both head lamp globes (low beam) do not work. It’s not a fuse issue as I understand there are separate fuses for each head lamp. Front parkers and high beams work fine. Surely not both globes have gone at the same time? Is there a common point of failure with these? It’s not the head light switch. 

I do have a towbar on this car. The tow bar installer fitted some box at the tail lights, I think it’s some kind of modulator. I also did rack weld some roof racks the other week on it but the battery was 100 percent disconnected

Bizarre stuff, explanations welcome ?

[Sol]

You could have a faulty BSI, it's the computer which connects all systems in the car together and runs all lights, reads all switches and is also the immobilizer. If you have damaged that then it's a total ball ache to fix.

Try a BSI reset, I posted the procedure in the how-to and tutorials section.

[Verl123]

Thanks for the response. There was a physical break in the back tail light though, that wouldn’t be bsi related?

[Sol]

No you're right, can you explain what you mean by a break?

[Drummond]

For rears, the top dual filament works as parking and brake light, and the bottom bulb is a fog lamp.

IDK whether the BSI uses fog lamps as a backup for brake if it finds the primary bulbs dead. Some non-PSA vehicles do that.

[Sol]

No, it just flags a bulb fail on the central display in the test section