2016 trailer brakes

[Rick01]

I have a 2016 mack granite dump truck.  I need air connection for tag trailer.  The truck has the red knob in cab.  The 7 pin wire connection is at the back of truck from factory but never used . The truck was originally ordered equipped for tag trailer but has never been used.  How do I identify where to connect the air lines ? 

[mechohaulic]

7 pin wire connection I would assume you are referring to a light plug  socket. ? is it mounted or tied behind crossmember ? reason asking is to determine how far  factory trailer set up you have.  are there capped off air lines or an air valve near  light plug or along frame ? ? don't think on that new a truck they even use a trolly valve any more . can you access behind the dash to see the red knob checking for capped line . seeing /knowing what you have is a strong determinization of how it is connected. tractor/ trailer protection valve needed??  glad hands or quick connectors for trailer air there or needed ??

[mechohaulic]

sure hope he comes back  with  follow up answers

[Joey Mack]

I would think that if the trailer button is installed, then the system is there..  My guess, is that he needs help with basic's.  I would like it if he raised the body and took pictures of the air plumbing, and also of the rear plate..  Like you said Mech, there may be capped lines..  

[fjh]

On 3/22/2024 at 7:06 AM, mechohaulic said:

7 pin wire connection I would assume you are referring to a light plug  socket. ? is it mounted or tied behind crossmember ? reason asking is to determine how far  factory trailer set up you have.  are there capped off air lines or an air valve near  light plug or along frame ? ? don't think on that new a truck they even use a trolly valve any more . can you access behind the dash to see the red knob checking for capped line . seeing /knowing what you have is a strong determinization of how it is connected. tractor/ trailer protection valve needed??  glad hands or quick connectors for trailer air there or needed ??

Yup go and look for a valve that looks like this! Bendix TP-3DC Trailer Protection Valve - P/N 109792 | eBay  and trace the lines! I'll bet they are there just capped off!

[mechohaulic]

12 hours ago, Joey Mack said:

I would think that if the trailer button is installed, then the system is there..  My guess, is that he needs help with basic's.  I would like it if he raised the body and took pictures of the air plumbing, and also of the rear plate..  Like you said Mech, there may be capped lines..  

another post which could be answered correctly IF it was accompanied with photos. trailer air set up by factory brand new ??? body shop installing dump installed air to trailer glad hands ??? no offence to author of post :: a few more specifics would be greatly appreciated. 

[mechohaulic]

based on "days of old" the factory would not run trailer air system on a unit UNLESS it was part of a large all the same order. red valve / 7 way wires would be factory installed. trailer air may have been on the order sheet, not necessary being installed at factory;; it's the selling dealer responsibility to complete along with dump body install ;; bringing in the third party (body shop) involved with the sell/set up. point is as prementioned, no picture no accurate answer possible.