Seneca air horns and air fill

[Robbbyr]

I don't recall seeing one, but I'll look again. I have 2 pressure gauges in my instrument panel and sometimes I hear the compressor noise from further back in the coach, instead from near the cab area, so I assume I have a secondary tank and maybe a secondary compressor.

You should only have one engine-driven air compressor.

Air brake-equipped trucks today have a "split" air system, much as hydraulic brake-equipped vehicles have a "dual" master cylinder and separate circuits. That is so a single failure doesn't cause all brakes to fail. You have a "primary" and "secondary" air system (with separate gauges) for each system in your Seneca. However it is one interconnected large system with two isolated sub-systems supplied by one air compressor (mounted to the engine).

As mentioned by another poster the "primary" system usually operates the rear axle brakes. Conversely, the "secondary" system usually operates the front brakes, and branching off the secondary system you usually have any air-operated accessories. This arrangement has been in place for years since on large trucks the rear brakes did most of the braking. So the front brakes were considered somewhat less important in the event of a failure. That isn't the general theory today, on newer trucks the front brakes now do contribute quite a bit to braking to reduce stopping distances.

The drawing below illustrates the two systems, however your motorhome does not have a tandem rear axle like a semi tractor. Just ignore the second set of rear brakes!

 

[jvteach77]

So tap into the tank I posted a picture of?

So does this mean it is ok to tap into the tank I posted a picture of in page 2 of this thread?

 

[Robbbyr]

So does this mean it is ok to tap into the tank I posted a picture of in page 2 of this thread?

Without knowing the plumbing layout of an air brake-equipped Seneca I can't say. My 2014 (without air brakes) has a much simpler air system. If you could have someone help you properly identify the tank layouts you would be in a better position to tap in safely. Ideally the rig would have an Accessory tank and that would be the best place to tie in. Otherwise, as mentioned by another poster, the secondary tank would be the next best choice, of course through a PPV. I have seen air accessories taken off the supply (wet) tank through a PPV, but generally that is not way things are done today.

Another option is a dedicated air horn compressor with a small reservoir thereby never tapping into your chassis air system at all.

Sorry I can't say better, but without a brake schematic or an hour under your rig on a creeper, I don't want to endanger your safety.

 

[jvteach77]

Success!

Thank to all who made suggestions, especially Robbbyr. I ended up having to tap into the air tank at the middle position where the pressure safety valve was. I put a T there and put the pressure safety valve on one branch of the T and the Pressure protection valve on the other. Then ran the line to my horn. I just disconnected my line from the electric horn and extended that line down to my horn so that it operates off the steering wheel button.

I really like the train horn and it is anything but subtle.

 

[brtnsnwbrds10]

question on connectors

Robbbyr is see your whole list and am looking to buy the stuff,
but on the back plate for the switch that freightliner used did it come with the appropriate connectors? or did you purchase those somewhere else too?
didn't see them on your list.

One of the things I was disappointed with on my Seneca is the really wimpy electric horn. My Focus toad has a far better stock horn! So I embarked on a mission to make things better by installing a set of real air horns. Since our Senecas have an onboard air system I decided to tap into it to accomplish the horns. And while I was at it I also decided to add an air accessory air port so I could fill my own tires or for whatever else I might need compressed air for.

To accomplish the air side I installed a 2.5 gallon auxiliary air tank fed from the chassis "wet" tank through a pressure protection valve. That valve is to ensure that the horn and air fill can never completely deplete the main air system. Then I ran an air line out of the new tank to the air horn mounting location on the right frame rail near the hood hinge. There the air line tees into the air fill regulator and to the horns themselves. Out of the regulator I have a female air quick disconnect. The horns are also mounted here behind the bumper for protection.

To operate the horns I still use the regular steering wheel horn button, but the circuit goes through a dash-mounted Electric/Air horns switch. So I can select either horn I want; a gentle electric "beep", or the sound of a locomotive bearing down! The selector switch is genuine Freightliner used on an American LaFrance fire truck, matches the other dash switches perfectly. I used the same switch connector on the back of the switch that Freightliner uses, so the wiring looks like the factory did it.

To view more pictures of the components please see the album here: Jayco RV Owners Forum - Robbbyr's Album: Seneca air horn and air fill addition

 

[Robbbyr]

Robbbyr is see your whole list and am looking to buy the stuff,
but on the back plate for the switch that freightliner used did it come with the appropriate connectors? or did you purchase those somewhere else too?
didn't see them on your list.

Welcome to the forum!

Here is a link to another page where I called out where I sourced the connectors. You could probably use off the shelf spade connectors if you wanted to, but I am somewhat of a perfectionist and I wanted it to look like Freightliner did it!

http://www.jaycoowners.com/forums/f5/seneca-modifications-39395-3.html

It is in the post from 09-14-2016, 04:30 PM. I just checked the part numbers I used online and they all still show as available from the supplier. Put the part number you are looking for in the search box of their website. Look only for the terminals since the search brings up other items like crimping tools.

Happy to help, please let me know if I can offer up any more information!

 

[Robbbyr]

Robbbyr is see your whole list and am looking to buy the stuff,
but on the back plate for the switch that freightliner used did it come with the appropriate connectors? or did you purchase those somewhere else too?
didn't see them on your list.

By the way what model and year Seneca do you have? Just curious!

 

[RoWest]

The wife and I put 7500 miles on these last 2-1/2 months in Canada. The far north logging trucks are a block long and sport 30 tires. Drivers are so immune to 'massive' that when honking my stock horn they probably crapped themselves laughing. Bought and installed the Viking electric horns at 125db and that should fix the 'can't heeear you' problem. VERY loud and easy install. California has a loudness limit of 110db for aftermarket horns, so will install the horn option switch for work-around.

 

[srxhare]

Hi Rob,
I have been reading your info on air horn install on Seneca.
can I ask what the purpose of the the Freightliner switch connector is ? Does the air horn switch on the dash somehow connect to this? Also what part of the dash did you mount the switch?
Thank you in advance

 

[srxhare]

That is helpful. My air tank has several more ports in the tank for me to tap into instead of having to add onto the fan clutch like you did. I was planning on removing the plug at one of the two positions on the right and running from there to my PPV and then on to my Horn. Where did you buy the fittings you used to connect the brake hose to the PPV and the horn?

Hi , I have been reading all the posts for adding Air horns to Seneca.
Which one of these ports in this pic did you end up using ? I have a 16 HJ that has air brake system . Did you use forward or rear tank?
Thanks
Ken Kvatsak

 

[Robbbyr]

Hi Rob,
I have been reading your info on air horn install on Seneca.
can I ask what the purpose of the the Freightliner switch connector is ? Does the air horn switch on the dash somehow connect to this? Also what part of the dash did you mount the switch?
Thank you in advance

I am just a bit of a perfectionist so I sourced and used a Freightliner selector switch, switch connector, and the wire inserts, so my wiring for my air horn/electric horn switch is virtually indistinguishable from the stock Freightliner wiring. But the connector is not necessary, the switch would accommodate spade lug connections as well.

The selector switch I installed merely directs the horn signal from the steering wheel button to either the stock electric horn or my installed air horns. I tapped into the horn wiring at the underhood electric horn itself, ran them back into the cab to the switch, and then back out to the electric horn and to the air horn. I wrapped it in wire loom and it matches all the original Freightliner wiring.

I put my air horn selector switch in the panel with all the other switches and I have added even more. I also installed stock Freightliner fog lights and their switch, and I also installed a cutout switch to disable the side view cameras so they don't display on the Navigation screen. For all 3 switches I used my Dremel to make an identical cutout to the other switches. The new switches are all to the right of my Even Brake monitor in the attached picture. The one marked "OPT" is the cutout switch for the sideview cameras.

 

[srxhare]

Hi JVTeach77, I saw your pic on the air tank for your air horn install , your 2017 have the same tank set up as my 2016 . Which port did you end up using? Also what size T or fitting did you end up using? I installed my air horns today using the same parts as Robby R ,Same install except he has a 2014 without air brakes.
Please let me know , maybe if you have any pics with your PPV.
Thank you Ken Kvatsak