There is a box next to the engine compartment fuse block that appears to be a box for two relays... Can anyone shed some light for its use? Here is a pic...

 

My truck has 2 relays in that plug. I dont know what they are for.

 

They are for the round 7-way trailer tow hook-up. They power the the aux/batt charge circuit and the trailer brakes. There is also a 30 amp maxi fuse in the distribution box under the hood that powers that relay box.

 

Its all making sense now, I recently bought this truck and took out the old brake controller to put in the new one and had nothing but trouble with using the factory plug and had to rewire it to make the darn thing work. Made me wonder why (what seemed to be the factory wiring in rear of truck) not function properly. Hopefully in the next few months i'll have all the stinking kinks worked out of it. Makes ya wanna kick the last guy that jerry'd this thing up, right in the nads.

Thanks for the information...

 

Actually, one is for reverse lights on the 7 way.

 

You are correct my friend. It has been awhile since I had to mess with mine.