Please help me with my air brake situation

ManDogBus · 05-26-2022, 05:20 PM

Please excuse my ignorance

Long time lurker but this is my first post.

I've read a few other threads on here but none of them seem to be quite the same situation I'm having.

I have a 2007 International that I'm converting to live in full time. I bought my bus in Phoenix AZ and drove it (approx 2 hours) to where I live in Tucson, this occured 2/14/22. I have not driven the bus since then, but regularly start my bus and let it idle for 10-20minutes.

My current problem is I'm getting ready to move my bus to another location where I will finish my build.

The Good:
Currently it starts up just fine, there aren't any alarms or buzzers going off. The air pressure gauges fill up to ~120psi, and when I use my brake pedal, it makes braking type sounds. The pressure dips when using them, then fills up again. I don't think I have a leak.

The Bad:
My emergency brakes won't disengage, when pressing or pulling the button, nothing noticeable happens. Since they won't disengage, I can't currently drive my bus. This makes me think it's an electrical issue.

There are a few possibilities that I am in the process of diagnosing, but perhaps there is another issue.

The likely problems:
I removed the hydraulic system for my front doors, see the attached picture. Perhaps being removed is telling the system the door is open, and thus the brakes are locked.

I disconnected some wiring to the wheelchair lift, perhaps there is a silent alarm or release button that I'm missing, which is locking the brakes. Since I am donating my lift, I would need to disengage these anyways.

I disconnected a lot of wiring elsewhere, but nothing on the dash. Perhaps I accidentaly disconnected the power to the release

Since I am out here in the desert, there is a possibility of packrats eating the power line to the brakes.

tldr;
Please help with any of the above or below
Wheelchair lift brake lock system
Front door brake lock system
If packrats were to eat a power line for brakes, other than under the hood, where should I look?
If the problem sounds like something else that I missed, please let me know

Thanks so much in advance!

Jolly Roger bus 223 · 05-26-2022, 05:26 PM

when you push the parking brake button in does it automatically pop back out on its own.
if not then your brake pads or likely rusted to the drums and might require you to have some wheel chocks and a helper to free them up.
oh and a decent hammer.

ManDogBus · 05-26-2022, 05:31 PM

Thanks for your quick reply
(Edit) It does appear to push itself back out.

Although rust is possible, my bus has never been in an environment conducive to rust. I would be very surprised if the brakes rusted over after 2 months of sitting in the dry heat. It's been 90-100 the last month with 1-5% humidity.

Is this similar to when people suggest banging the brake pads, or rock between drive and reverse to attempt to free the brakes?

TheHubbardBus · 05-26-2022, 05:37 PM

So are you just assuming your brakes are engaged and preventing the bus from moving, or have you confirmed this? Is it possible it's not brake-related at all?

I agree with you: I find it unlikely your brakes would have rusted to the rotors after sitting the past 2 months out here (also in AZ SW). I can't even remember the last time it rained.

ManDogBus · 05-26-2022, 05:43 PM

I'm assuming, I don't have much knowledge in terms of auto mechanics.

When revving the engine in drive, the bus does not move, but does appear to surge slightly. Therefore I'm assuming it's brake related.

(edit) Attached is a shot of my gauges and everything after running for approximately 1 minute. The parking brake button on the right can be pushed in but immediately pushes back out. Pedal brake engaged, testing in R N & D. No apparent air sounds happen other than from when using the brake pedal.

All door hatches are firmly in the closed position.

Jolly Roger bus 223 · 05-26-2022, 05:54 PM

i have stayed in the hot dry climates as well.
it could be something as simple as the pushrod or cams on the brake system

ManDogBus · 05-26-2022, 06:06 PM

Quote:

Originally Posted by Jolly Roger bus 223

it could be something as simple as the pushrod or cams on the brake system

Thanks, is there a reason this would have happened after 2 months of sitting in a parked position? I guess I'm figuring there are thousands of things it could be, busses are mechanicaly complex. I am going to try for the most likely problems, hoping it's an easy fix.

How do I test or inspect for this? I am searching YT and have not yet found anything useful.

ewo1 · 05-26-2022, 06:25 PM

Quote:

Originally Posted by ManDogBus

Thanks, is there a reason this would have happened after 2 months of sitting in a parked position? I guess I'm figuring there are thousands of things it could be, busses are mechanicaly complex. I am going to try for the most likely problems, hoping it's an easy fix.

How do I test or inspect for this? I am searching YT and have not yet found anything useful.

Your bus has a wheel chair interlock device that will not allow the bus to roll when it thinks the wheelchair lift is in use.

I read this on page 167 Of this doc -> https://www.leonardbus.com/staging/w...ual-4-2020.pdf

Which is an operators manual for your bus.
Since you removed some wires I would look in that direction first.

This next doc is for wiring on busses 2011 and newer.
Chapter 15 has wiring diagrams for the interlock circuit. Take a look to see if it is similar to what you have.
Diagrams start on page 369 of the doc.

http://bodybuilder.navistar.com/Gene...0000003601.pdf

Good luck and keep us posted.

ManDogBus · 05-26-2022, 06:57 PM

Thanks so much for links to these manuals!

Quote:

Originally Posted by ewo1

Your bus has a wheel chair interlock device that will not allow the bus to roll when it thinks the wheelchair lift is in use.

This is what I had assumed. I don't think I cut any wires for the lift, just unplugged them. I was hoping a disconnected system would not trip any alarms/failsafes.

I'll attempt to reconnect now, I know it doesn't currently have power, as an inoperable lift would (hopefully) deter entry through this doorway. If it works when the power is restored, then that should be an easy fix.

However, I will be donating my wheelchair lift soon, and I would need to remove this interlock device if it exists, or else I won't be able to leave their lot once it's removed. I will check with the company removing the lift, but if anyone here can help me disable that system then I won't need to worry about disconnected wiring issues

Jolly Roger bus 223 · 05-26-2022, 06:57 PM

use the search on hear for air brake inspection or something of the kind and see what you get.
i know them but its hard to explain online and not knowing how safe you are being when working under the bus.
but there is air brake stuff in this forum to read before you go playing with stuff that can walk you through the entire system or i dont recommend but you tube university air brake inspections.
and yes if your button is not pushing out on its and you are holding pressure then i myself think you have a brake drum or related component not releasing.
at that point i am talking about the rocking back and forth idea before you crawl under without wheel chocks and not the ones for cars and a helper to be in the bus with the brake pedal under foot while you are under it if you go the hammer method.

rossvtaylor · 05-26-2022, 06:59 PM

Hey MDB...this is a basic thought and not meant to sound too obvious...but I didn't read that you're applying a firm pressure on the brake pedal when trying to release the parking brake. If you don't, you'll get the symptoms you describe.

IF you are pushing the brake pedal when releasing the parking brake, and it still acts up, then I believe it's an interlock solenoid related to either the front door or (more likely) the lift mechanism.

ManDogBus · 05-26-2022, 07:11 PM

Quote:

Originally Posted by Jolly Roger bus 223

and yes if your button is not pushing out on its and you are holding pressure then i myself think you have a brake drum or related component not releasing.

I misspoke before, the button is pushing out on it's own. To reiterate, the yellow parking break button will not stay "down" but is remaining "pulled"

I won't be hitting or releasing anything without properly sized chocks and another person. I have been searching on this forum also, but I need a visual comparison or I will likely get lost.

Quote:

Originally Posted by rossvtaylor

IF you are pushing the brake pedal when releasing the parking brake, and it still acts up, then I believe it's an interlock solenoid related to either the front door or (more likely) the lift mechanism.

I am pressing the brake pedal before shifting, and keeping it pressed while attemping to disengage the parking brake.

Thanks for checking just in case. I know this is like the "is it plugged in" kind of obvious question, but it's always good to check just in case.

Jolly Roger bus 223 · 05-26-2022, 07:15 PM

sorry ross this might be a stupid question from me.
would the park brake button still not push back out to keep the brakes locked?
i understand the lift and door interlock stuff and i am not on your level by any means and i am probably under thinking this just because of what makes since and probably because i spent my week at work checking everything that makes since was right and it ended up being something that dont make since but it was the fix until i get answers from the factory.
sorry for the little rant. that is industrial heating and air with a factory out of canada?
i shut up now

Jolly Roger bus 223 · 05-26-2022, 07:22 PM

my big bus below 60- 90 psi the button will pop out and not stay in until like 110- 120 psi if i hit the brakes at 110-120 psi it will pop out because it drops below that.
my air pressure is around 160 normal.
did you have an air actuated front door that you disconnected?
you mentioned actuator removal.
you will never build proper air pressure to release the brakes with a 1/4" line leaking.
these are all assumptions.

ManDogBus · 05-26-2022, 07:35 PM

Quote:

Originally Posted by Jolly Roger bus 223

did you have an air actuated front door that you disconnected?
you mentioned actuator removal.
you will never build proper air pressure to release the brakes with a 1/4" line leaking.
these are all assumptions.

My bus won't go above 150psi according to the gauge. Below 60 I get a warning sound and light. I did remove a front door air system. The picture should be in the original post. The 1/4" tube that was connected is currently plugged and not leaking. Other than disconnecting the power, I didn't do anything else with the front door. Perhaps it has its own interlock failsafe.

I hooked up the wheelchair lift and it works perfectly. I put it back in it's "stowed" position. Parking brake still won't disengage.

turf · 05-26-2022, 07:45 PM

i would do a couple of things:

chock the tires, and get under there while someone else pushes the button in. to me, the system is detecting a fault and not closed. maybe having an assistant push the button will reveal where the air leak is.

still no luck? figure out which tire/axle is causing your issue, is it one tire or all of them? this will help narrow down your fault.

i tend to think from your description its related to the air door removal. but the interlock with the wheelchair door makes sense too.

can't you just take power away from an interlock relay and bypass them? idk

good luck

ManDogBus · 05-26-2022, 07:51 PM

Although I could be wrong, I don't think there is an air leak. I think the problem is circuit related. My pressure is stable and fills quickly.

How could I tell one or any of the tires are at fault, visually seeing some brakes disengage but not others?

My parking break knob is giving no response currently. No air sounds when pressed or pulled. Pushing in for a minute does nothing noticeable.

Quote:

Originally Posted by turf

can't you just take power away from an interlock relay and bypass them? idk

good luck

I have no idea if this would work and would love someone's insight on this. I'm guessing there is an interlock relay for the front door also.

Can anyone help me with the steps of disabling the interlock brake fail-safes for the front door and wheelchair lift. Possibly just disconnect them all until I'm done building.

Dbacks2k4 · 05-26-2022, 07:59 PM

Could be a newer style parking brake release knob like Ross mentioned, the parking brake knob will not push in unless you're firmly pressing down on the brake petal at the same time. None of my 2005-2006 ICs have that, but one 2008 IC did.

More likely is a sensor/interconnect attached to the wheelchair lift/door. I've never seen an interconnect on the front door in that generation IC

ManDogBus · 05-26-2022, 08:01 PM

Quote:

Originally Posted by Dbacks2k4

the parking brake knob will not push in unless you're firmly pressing down on the brake petal at the same time. None of my 2005-2006 ICs have that, but one 2008 IC did.

More likely is a sensor/interconnect attached to the wheelchair lift/door.

I am pressing the brake pedal fully when testing the parking brake knob

To fix this issue, can I, and if yes, how do I disconnect that sensor?

Dbacks2k4 · 05-26-2022, 08:03 PM

Quote:

Originally Posted by ManDogBus

I am pressing the brake pedal fully when testing the parking brake knob

To fix this issue, can I, and if yes, how do I disconnect that sensor?

I would first reconnect the wheelchair lift if you can and see if the parking brakes release. That'll tell you for sure where your issue is. If they still don't release we have another problem to chase.

If they do release once the lift is reconnected, then you can go about removing the interconnect. Usually it means jumping a couple wires together somewhere to complete the circuit. I'm not an expert at tracing those out...

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