2005 f150 xlt

I recently bought a 7 pin to 4 pin trailer light adapter, plugged it and hooked up the trailer lights aaaannnddd nothing works...so I checked the fuse panel to make sure I had the relay in which it was and all fuses are good...tested the 7 pin on my truck and it works and is getting power so I figured maybe just maybe I got a bad adapter so I took it apart and all the wires lined up right, so I went and exchanged the adapter for a new one AND got my dads which I know works....still doesn't work, everything on my trailer side works...i took my test light hooked the ground to the ground on the 4 pin side and put the light on the hole nothing comes on, when I put the ground on the test light to the truck and the light on the 4 pin, it works...so basically the ground on the adapter isn't working for some reason, does anyone have this problem? Any input will help thanks

 

If the 7 pin trailer tow adapter is working as it should, the problem points to the adapter you are using.

The pinout on the 7 pin on the truck :


Make sure the adapter is using the ground at ~ 7:00 position on the RV plug, not something else as it sounds like it is doing.

Set meter to resistance or continuity and check from that pin ( mirror image on the adapter you have, so ~ 5:00 position ) to the bare pin on the flat 4 plug for continuity.
If this does not work, you do no have the correct adapter.

 

Are you checking this with the trailer NOT hitched to the truck? That may make a difference. Sscully is the smart one here, I'm just throwing out a possible maybe.

 

Ya I made sure the adapter had all the right holes being used, even got the test light out to make sure which were the turnlights/taillights and park lights....but some way some how I ended figuring it out, my 7 pin must be a little smaller than that adapter so I bent the metal clips in a little on the adapter on the 7 pin side, put a little grease on there and wham bam thank you ma'am she works like a champ