Technical brake light issue

[sprie]

I replaced a faulty reversing camera. The power to the wireless camera was tied to the side lights.
During the installation i noticed that
a) the brake lights come on when the side lights are turned on
b) and when the side lights are not turned on, when the brake pedal is pressed, both the brake lights and the side lights come on.
Both sides.

I obviously need to fix this.

Any suggestions of which end of the van to start the investigation (could it be tail light cluster or is it somewhere near the brake pedal)?

 

[ZaphodB]

I replaced a faulty reversing camera. The power to the wireless camera was tied to the side lights.
During the installation i noticed that
a) the brake lights come on when the side lights are turned on
b) and when the side lights are not turned on, when the brake pedal is pressed, both the brake lights and the side lights come on.
Both sides.

I obviously need to fix this.

Any suggestions of which end of the van to start the investigation (could it be tail light cluster or is it somewhere near the brake pedal)?

Bad earth at one or both of the light fittings.

 

[sprie]

Bad earth at one or both of the light fittings.

Think you are right.

Cleaned up both clusters but no change.
Disconnected all the wires from nearside cluster: when i turned on sidelights, the brake lights on offside cluster did NOT come on.
The nearside cluster is very corroded (plastic bits come off in my hand when i move it) so I think that cluster may be the issue.
I will get a replacement, hopefully (fingers crossed) that sorts out the issue.
thanks

 

[sprie]

Think you are right.

Cleaned up both clusters but no change.
Disconnected all the wires from nearside cluster: when i turned on sidelights, the brake lights on offside cluster did NOT come on.
The nearside cluster is very corroded (plastic bits come off in my hand when i move it) so I think that cluster may be the issue.
I will get a replacement, hopefully (fingers crossed) that sorts out the issue.
thanks

I found the issue.

I did various tests of connectivity to earth / to each other across the various wires, and there was clearly connectivity between the wires that lead to side lights and brake lights. And then i realised what was the likely issue.
I had had a missing tow ball when i bought the van, so when i replaced the ball i thought i would upgrade the connector from the old 7 pin to newer 13 pin. Whilst i had done a good job creating a series of spade connectors, when i had bound it all together, i had left an issue with the tail of the connectors. When i unbound it and separated the wires, the issue disappeared. Easy fix involved just some better use of insulation tape.
So it was my fault!

As a side issue, the passenger side cluster internal plastic was like paper - if you touched it, it fell apart. I tried to find a Ducato replacement, but found that the connector was neither the "round pin" nor the "square pin" Ducato connector. It turned out to be a Cobo trailer light. Don't know why. But it has fitted nicely, so it was the right replacement.