trailer wiring mystery box

It's probably the flux capacitor :wink: ...seems an intricate bit of kit where a few diodes correctly wired should protect the BECM from voltage spikes...
? on a more serious note...what is it supposed to convert? perhaps some sort of electric brake controller?

couldnt figure it out really. plugged into the trailer harness, the other end goes to the 7pin plug into the bumper. non of the output signals seemed to work, so i cut the whole box out and now my trailer lights work properly. Maybe a diode in each wire would protect from an electrical problem, easy enough to figure out. Any new trailers I'll forst test with my discovery, I think it's more forgiving. Germanium didodes only drop .3 volts, cheap insurance

Have a look at the actual connection to the truck. My instructions told me to connect red to white and white to red. Genuine part too, didn't work.