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rommel · 04-29-2019, 09:32 AM

I have a air line coming from the 2001 36fd2s alpine coach to supply air to the cylinder that applies the brakes on the toad. It quit working and I'm not sure how it's plumbed or operated. Is there a solenoid involved? If so where would they put a switch.

Old Scout · 04-29-2019, 11:42 AM

….Aux. air supply for toad braking is an after-market add-on to the std Alpine configuration. You will need to determine what make and model of toad braking system you have and then see if some one knows how it works and how to diagnose it.

rommel · 04-29-2019, 11:55 AM

The system was on the coach when I bought it, I added the tow package later. Just though that there was some kind of standard. Thanks anyway

RVPioneer · 04-29-2019, 01:02 PM

Can you clarify if it is the air supply from the coach that quit working (supplying air) or the toad braking system that quit working? Also, did the toad and braking system previously function properly with your Alpine?

rommel · 04-30-2019, 07:38 AM

It all worked well for the last 11 years, she's getting old and so am I. It lost air from the coach, I'm trying to find out what they use to trigger the air to the cylinder, is it a pressure switch from the brake system, limit switch from the pedal, or electrical from the brake lights. I'm in the process of trying to track the air line back, but man do those things disappear in dark holes. If I knew what to look for it would help.

Old Scout · 04-30-2019, 11:07 AM

You are on the wrong track--Alpines [except the Avalanche] have hydraulic service brakes.. Air is only used for suspension and to "release" the parking brake....accordingly, most Alpiners have no idea what you are asking....so think: are air bags working?....is the parking brake working?....what you do have is an after market tap-in to the OEM air system that provides air for your toad braking system....you didn't say--but to start, do you have air at the rear port where you plug in your toad braking system?....

rrthor · 04-30-2019, 12:37 PM

Maybe I can help. Do you have a M&G braking system. If so on the toad you will have an M&G air cylinder in between the master cylinder and the vacuum canister. If that is the case there will be a proportioning valve mounted some where near the rear of the coach. This valve will have a hydraulic connection to the rear brakes. It will also have a connection from the coach's air system. There will be another air connection that goes to the rear of the coach and out to the toad. There is one more connection but it is just a vent. On the top of this valve is a knob to adjust the amount of air pressure going to the toad given a certain amount pressure from the coaches brakes.

I am not saying you need to adjust the adjustment knob just trying to help you find the valve. Also maybe your system is not an M&G system.

RVPioneer · 04-30-2019, 01:08 PM

OP stated in #5 that he no longer has air pressure to the presumably after market air line that has supplied air for the past 11 years. Anything is possible but it seems unlikely that said air line would have a solenoid or relay to control air flow. Possibly a manual shut off valve after the point it was tapped into the existing line?

What braking system is on the toad?
Have you tried connecting the toad to a known pressurized air system to test for proper function?

Old Scout · 04-30-2019, 01:34 PM

…..I am kind of simple about things like this -- a female air chucks, exposed to the elements, have been known to fail to open. Really hard to know what the OPs level of technical expertise is, so I tend to start with the obvious first....

kraig · 05-02-2019, 11:30 PM

It is possible it is Roadmaster Brakemaster. There are two versions. One is for MH with air brakes. There is also one for hydraulic brakes that comes with an air compressor to operate the brakes for the toad. There is a solenoid valve that hooks into the brake supply line and the needs air supply to operate air brake for the for the toad. It is possible the air compressor is not working or the solenoid valve is not working. To see if you are getting air to toad, go to the back of the MH air disconnect. Unscrew the female coupling, Step on brake pedal and see if air comes out. If no air, It could be a bad valve or no air supply. The solenoid you could order from RM.

If it does have a Roadmaster air compressor that is not working, you don't to replace it. There is already an air compressor for the airbags that should work your brakes fine. Just hook into your air compressor tank or tee in to a line.

I never used the RM air compressor and hooked up this way and my toad brakes work great.

rommel · 05-04-2019, 06:05 AM

Thanks for all the advice everyone but problem solved. I knew Alpine is all hydraulic breaks as are most if not all disc brakes. I was hoping that some one knew where the aftermarket system would have been mounted. There is a switch mounted on the brake pedal linkage up front near the master cylinder and the solenoid valve that supplies the air to the cylinder in the toad is mounted next to the air bag leveling valve. That was located in the well for the rear suspension. They tap the air for the aftermarket system from the air bags. Tracing the system took a while but it all came down to, guess what? A broken wire. Thanks again.