2007 NBS - trailer lights both flash when signal left or right

[burnt03]

2007 NBS Silverado

- truck lights work fine

- plug into trailer, signal left or right and both trailer lights flash.  
- tried diff trailer, same thing.  
- Truck/trailer plug connectors are good.  
- unplugged the connectors under the bed (back of 7 pin, 4 connectors at main block under bed).  Big pin at back of 7-pin was a bit corroded, sanded down, cleaned out and greased.  Same thing.

- nothing odd under there (ie. new damage that could’ve pinched wires)  

 

Ideas?  Pull loom and check all wires for cuts/frays/corrosion?  Is there a specific ground at that rear block that I could check?

Thanks 

[richard wysong]

try running a separate ground to the trailer, you could use a jumper cable to see if that cures the problem and if it does rig up something permanent. I put self drilling screws with crimp on ring terminals on my hitch and trailer with male/female spade connectors for the disconnect on my trailer after the ground wire in the plug broke