Help please! Hayes brake controller installation

[Cowboy924]

Hello! Long time lurker, first time posting. I’m trying to install a Hayes brake controller in my new to me 2012 Volvo VNM630. Which air line do I “T” into? I’m fairly mechanically able, but air brakes are new to me. I attached pics (I hope) of the air lines under the dash and under the hood. Any help would be greatly appreciated.

 Thanks, Luke

[Darryl&Rita]

Under the dash, find the line that goes to the "Brake Application" pressure gauge. Tee in anywhere on that line, or the line it tees into.

ETA: Learn your air brake system, before it teaches you an expensive lesson. 

[Cowboy924]

My applied pressure gauge is electric, no air line going to the back of it. That’s the first place I looked. Thanks

[Darryl&Rita]

Ok, follow the wiring to the pressure transducer. Tie into that line. 

[Cowboy924]

Here’s a pic of the back of my instrument cluster.

i don’t know which wires go to the brake pressure gauge. And even if I did I’m not sure I could keep track of which “white with an orange” stripe wire it is LOL!

seriously though, I thought somebody on here must have already been through this and could point me in the right direction.

 Thanks, Luke

[Nigel]

Luke

The fellow that did mine disconnected one line at a time until he found one that had air coming out of it only when the brake pedal was pushed.  That will be suitable to t into. I suspect one of the small lines going into the black firewall pass thru will work as the pressure transducers are on the inside of the pass thru.  Mine is t’d into one of the larger lines right above the steering column but my truck is a couple of thousand miles away so I can’t tell you which one.  

Nigel

[Darryl&Rita]

The wires should have numbers printed on them. Match the numbers at the gauge to wires on anything that looks like it has air lines connected to it. In your first pic, it looks like a collection of switches and transducers. One will be brake lights, one Cruise control disconnect. These will be switches. The transducer will also be in there. (I  think)

[Cowboy924]

Upon closer inspection, the black pass through panel is marked at each location. Once I found the transducer marked “APP G” it was pretty easy to figure out which air line I needed. I double checked it using Nigel’s method.

Its the black line pointed out in the picture below, in case anyone else needs to know.

I’ll post more pics once I get it installed. Thank you both for your help!

[Nigel]

Thanks for letting us know Luke.

[Darryl&Rita]

Agreed, thanks. I like to use the application gauge feed, as it will indicate pressure from either the foot treadle valve, or the hand valve for the trailer brakes. This can come in handy when doing a tug test after hitching up, as well as controlling the brakes on the trailer in time with the truck brakes.

[runaway parents]

Could you tap into the service brake side of the trailer brakes then cap of the glad hands?

 

[chief916]

I came off of my brake light switch.  I put a inline T fitting.

[Nigel]

runaway parents. I think you could do exactly that but don’t forget to push in the red trailer service knob or you will have no trailer brakes, not quite idiot proof.  

Nigel

[runaway parents]

9 hours ago, Nigel said:

runaway parents. I think you could do exactly that but don’t forget to push in the red trailer service knob or you will have no trailer brakes, not quite idiot proof.  

Nigel

Don't real truck drivers do this every time they hook up a trailer? Should be easy to remember. Buy tapping into the service brake line you should be able to use the Johnson bar to activate brakes buy hand.

[Darryl&Rita]

If you're not pushing in the red knob, you're driving around without full braking capacity. Don't do it with the trailer on the hitch. 

[GlennWest]

That's easy for me to remember. I have air over hydraulic brakes. My trailer brakes are locked down until I push red in