2013 Cascadia- No Trailer lights

Sam chassis module is probably corroded internally from water. Pull plugs at bottom of module and look for "green corrosion" The relays also go bad quite often. If you don't have extra swap with known good ones for testing. Good luck.

 

first small relays must be checked. these relays are chinese .

 

What I would do is this considering just the tail lights on the trailer was the first issue .... test each pin on the trailer cord using the cords ground with a test light or multimeter. If none of the pins on the trailer cord seem to be working ground the test light or multimeter to the frame then test each pin on the cord. If now you have power at the pins when grounding to the frame a bad ground in the cord is the issue. Still if none of the terminals are working, pull the cord out and test from the plug that is attached to the back of the cab. Probe the ground on the cab plug and test each terminal you seem to have power you know the cord is damaged. If still no power ground to frame again and test each terminal on the cab mounted plug.if you have power at the pins now its gunna be a bad ground at your plug. If no power still, go to the Sam chassis. I'll look up the next step from the Sam chassis and post. Also... check the trailer 7way light box for ground issues/ blown breakers on the brown and or black circuit.