truck cap 3rd brake light
 

I am trying to hook up my 3rd brake light on my cap..its on a 2010 stx...
I have read that there is a green wire that Ford left us just for this purpose..green wire sticking out by itself labeled es-1 directly under the master cylinder..shrink tubing over the end of it
I checked the wire for power with the brake on/off...it does get power when the brake is on..
tried to pick up a temporary ground near the tailgate stiker post to verify that this will work..now I have no power on this green wire..
can't seem to find a blown fuse.
what am I missing?
should I have used the ground/black wire near the fuse box on the radiator support...it sticks out like the green one and it is labeled es-1 as well..

looked at the wiring hook up on here before I thought but searching doesn,t show anything for me..

thanks

any ideas?

Does the trailer wiring relay/fuses etc have to be plugged in?

Well, I had power on that wire only when the brake was on when I started. nothing had changed ecept that I lost power on that wire ..

I spliced into that wire and ran the wire on the ground next to the truck,at the cap,wire nutted temporarily to the brake light and tried to pick up a ground off the tailgate striker post to verify operation of the light...

must have shorted out,but cant seem to find a blown fuse...and everything works cept for power to that wire..maybe took out a relay?
looks like we still have power to the trailer pigtail...

thanks

Sure you have a good ground? When I hooked up the third brake light on a truck cap on the 97 F 150 I just had, I had to ground the light to the frame of the truck. Just couldn't get a decent ground anywhere else.

I picked power up for that light from the third light that was original to the truck.

It should be fuse 82 in the battery junction box, 10 amp and it is the green wire. try checking that fuse.

That wire may already be grounded

[quote=countryboy69;10385097]It should be fuse 82 in the battery junction box, 10 amp and it is the green wire. try checking that fuse.[/quote

I looked at them all,but I am going out right now to check that one..Ipulled many and checked them with a meter instead of just a visual look..
that fuse is only for that purpose isn't it?


pulled fuse checked with meter...good fuse...then checked for power on green wire with brake on and we now have power...?

would you happen to know what the short wire that comes out of the battery box is for...it says es-1 but,it is a black wire..

thanks for your help..