Going crazy trying to make lights work, jumpered them with a battery charger, worked fine, checked prewired GM fitting, worked fine, Pluged the trailer in, hooked up everthing, no tail ,no turn no brake. Did it all again, twice, nothing, waited acouple of days, tried it again, but this time turned the head lite switch to full on,and started the motor and TADA, they work!!! The GM's have a cuttoff in the switch that works with the Daytime running lights to keep your battery from running down when hooked to a trailer, and motor is off.
Junk is something you've kept for years
And throw away three weeks before you need it.