oki will bite ! what box are you talking about and what truck ?

 

1999 suburban... it does not have the brake wiring plug in fuse box. I cant find the power wire from brake switch so im looking for another source to connect the brake wire too. Any help????

 

you must hav e a classic body style truck ,look's like a 1998 .they are not pre wired for the control you will have to hard wire the controler into the truck i am sorry to say !
i only now a few thing's you can look for,you can look to see if there is a factory harness tied up either by the spaire tire that will have the light wire's and brake controler big blue wire and red 12 volt lead wire .take a look in the owner's manual it may tell you about it .so you can hook up a trailer plug ,the other end of the brake control blue wire and red power 12 vt lead wire may be tied up behind the brake booster at the fire wall that you can pull out and run the blue wire inside the cab to the control and the red wire (it may be orange ) to the battery if you need a 12 volt lead at the plug .
i know you will have to tap into the cold side of the brake light switch .
other wise go to a shop and have it installed . good luck !