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Old 02-16-2021, 05:25 PM   #1
Mini-Skoolie
 
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Air parking brake locked

I recently purchased a bud and am beginning conversions at my parents house in Connecticut. It’s is a 2011 international defender with a maxxxforce engine and Allison push button transmission .

The bus is not registered yet but I like to move it up and down the drive way as to not let it sit too long and today when I went to move it I could not get the parking brake to release. When I push the yellow button it doesn’t even feel like it wants to go in far enough.

Any tips or advise on how to trouble shoot this?

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Old 02-16-2021, 06:47 PM   #2
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welcome.
we tend to shy away from the newer stuff.
there will be someone here that can help more than me but airbrakes are airbrakes.
that button usually wont push in below 60PSI and that is its very minimum release pressure at 90 psi you should be able to push the brake pedal a few times and it pop back out.
if your guages and or system are not reading those pressures then you have an air leak somewhere.
do you have airbag suspension?
do you have air ride seat?
more info of your bus will help us help you.
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Old 02-16-2021, 07:32 PM   #3
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If you're building up air then you should be able to push in the parking brake valve and it stay in. If this is happening but you still cannot move then you may have a frozen brake. In Connecticut in this weather I wouldn't be surprised if this is the case. But let's eliminate the obvious stuff first.
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Old 02-16-2021, 07:48 PM   #4
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I agree. Air pressure must be built up to at least 90 psi before you can even try to release them. If this is the case, then you need to learn more about how air brake systems work on your bus.
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Old 02-16-2021, 08:26 PM   #5
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Quote:
Originally Posted by Jolly Roger bus 223 View Post
welcome.
we tend to shy away from the newer stuff.
there will be someone here that can help more than me but airbrakes are airbrakes.
that button usually wont push in below 60PSI and that is its very minimum release pressure at 90 psi you should be able to push the brake pedal a few times and it pop back out.
if your guages and or system are not reading those pressures then you have an air leak somewhere.
do you have airbag suspension?
do you have air ride seat?
more info of your bus will help us help you.
I do have air ride drivers seat but I am not sure about the suspension. The thing is that while I was trying to release the brake today the gauges for both air brakes 1 and 2 read above 90 which is what I thought was weird.
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Old 02-16-2021, 09:12 PM   #6
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If the yellow knob stays in, then you either have stuck shoes, or moisture in the lines that froze. I will bet good money that the bus is equipped with an air dryer, but many that are not experienced with air brake systems, hear that and tend to believe that is all that is needed. You will still have tank drains and they need to be drained at regular intervals.



Likely stuck shoes. If so, this is very common, don't let it worry you. You can get them broke loose. If the yellow knob stays in and you have the engine warmed up a bit, then try rocking the bus forward in low, then backward in reverse, keeping mind that when the brake shoes pop loose, the bus will lurch in the direction you have the trans in. So be prepared to hit the brakes to stop. Let us know if this works before going to the more extreme measures to break them free.


Since you mention maxxforce engine, did any service records come with the bus? There was a egr recall that should have performed.
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Old 02-17-2021, 09:39 AM   #7
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Video of problem

Thanks for the help I tried rocking backing and forth and nothing yet. I’ve attached a photo (wouldn’t upload the video) to show how the yellow button won’t go in to disengage the break, the air pressure is up and my foots on the break.
Attached Thumbnails
A423EEA3-0180-4024-9145-80A8BFB90A5A.jpg   1209811E-C7AB-459D-B880-718FB19EC98C.jpg   AB2BE837-80E1-41F4-8964-B56E0B71E0A3.jpg  
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Old 02-17-2021, 09:57 AM   #8
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This is definitely odd and it seems like you're not doing anything wrong. That yellow button is supposed to pop out, and activate the parking brake, when the air pressure drops too low. But your gauges indicate you've got proper pressure in the tanks...so that tells me the air pressure at the valve is too low and I don't know why that would happen. We don't have any bus new/recent enough to have an interlock in that circuit, but I'm guessing that's what's going on. The button not staying depressed leads me to believe it's not an issue of frozen brake shoes.

If you press the button and hold it down, keeping it depressed, do the brakes release while you're doing that? Have you recently removed any door or window switches or wiring?
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Old 02-17-2021, 10:07 AM   #9
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Does this have a wheel chair lift?

Sometimes there is a safety interlock on the doors that won't let you release the parking brake if the door is opened.

I'm not familiar with the IC defender, or any of the cutaway style buses.
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Old 02-17-2021, 10:10 AM   #10
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Originally Posted by rossvtaylor View Post
This is definitely odd and it seems like you're not doing anything wrong. That yellow button is supposed to pop out, and activate the parking brake, when the air pressure drops too low. But your gauges indicate you've got proper pressure in the tanks...so that tells me the air pressure at the valve is too low and I don't know why that would happen. We don't have any bus new/recent enough to have an interlock in that circuit, but I'm guessing that's what's going on. The button not staying depressed leads me to believe it's not an issue of frozen brake shoes.

If you press the button and hold it down, keeping it depressed, do the brakes release while you're doing that? Have you recently removed any door or window switches or wiring?
The air brake will release while the bus is off but not while it’s on. And if I release while it’s off and start the bus it will reengage. I did work on the air doors but they seem to have their own compressor and still function. I also removed all the speaker and over head light wires that I traced back to around the door but I thought I was careful and they weren’t attached to anything. Maybe something was knocked loose while I un plugged them because they all ran to right by the door and that’s where I stopped tracing them I didn’t unplug anything from the fuse box directly just partially down the line to where there were like clip plugs above the door
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Old 02-17-2021, 10:10 AM   #11
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Quote:
Originally Posted by rossvtaylor View Post
This is definitely odd and it seems like you're not doing anything wrong. That yellow button is supposed to pop out, and activate the parking brake, when the air pressure drops too low. But your gauges indicate you've got proper pressure in the tanks...so that tells me the air pressure at the valve is too low and I don't know why that would happen. We don't have any bus new/recent enough to have an interlock in that circuit, but I'm guessing that's what's going on. The button not staying depressed leads me to believe it's not an issue of frozen brake shoes.

If you press the button and hold it down, keeping it depressed, do the brakes release while you're doing that? Have you recently removed any door or window switches or wiring?

This is a very good point about the door and window safety switches etc. There will be a considerable amount of electronics with this brake system as it will have antilock brakes.

Did you receive any type of owners manual with the bus? Only 10 years old, I would think literature should be available somewhere.
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Old 02-17-2021, 10:13 AM   #12
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Originally Posted by Goingmerry View Post
The air brake will release while the bus is off but not while it’s on. And if I release while it’s off and start the bus it will reengage. I did work on the air doors but they seem to have their own compressor and still function. I also removed all the speaker and over head light wires that I traced back to around the door but I thought I was careful and they weren’t attached to anything. Maybe something was knocked loose while I un plugged them because they all ran to right by the door and that’s where I stopped tracing them I didn’t unplug anything from the fuse box directly just partially down the line to where there were like clip plugs above the door

Awesome diagnostic. So it is a safety system of some kind. Any check engine lights or flashing lights in the dash?
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Old 02-17-2021, 10:15 AM   #13
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Quote:
Originally Posted by Goingmerry View Post
The air brake will release while the bus is off but not while it’s on. And if I release while it’s off and start the bus it will reengage.
Interlock! This is helpful info, because the air switch itself is mechanical and seems to work without power (the bus off) but when you apply power, some solenoid is activated in a safety circuit. So I think you've narrowed the issue to an interlock. Start looking at all the wires and connectors you might have touched or damaged, plus all door switches. I think your issue is there and not in the brakes themselves. Progress!
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Old 02-17-2021, 11:26 AM   #14
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Our bus works similar... If the system thinks the doors are open or e windows are unlocked you can start it but the e brake will not disengage and the tranny can not be put in drive or reverse.

Check the micro switches on the doors.

Johan
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Old 02-17-2021, 11:39 AM   #15
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Quote:
Originally Posted by rossvtaylor View Post
This is definitely odd and it seems like you're not doing anything wrong. That yellow button is supposed to pop out, and activate the parking brake, when the air pressure drops too low. But your gauges indicate you've got proper pressure in the tanks...so that tells me the air pressure at the valve is too low and I don't know why that would happen. We don't have any bus new/recent enough to have an interlock in that circuit, but I'm guessing that's what's going on. The button not staying depressed leads me to believe it's not an issue of frozen brake shoes.

If you press the button and hold it down, keeping it depressed, do the brakes release while you're doing that? Have you recently removed any door or window switches or wiring?
It does have a wheel chair lift, I’ll start looking at connections but they all seem fine to me but I feel like you are all right because the logic seems very sound to me. I appreciate the help folks, you are all great.
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Old 02-17-2021, 11:41 AM   #16
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Is there a way to work around the interlock system with the wheel chair door because I’m thinking that might have been disconnected and that I messed up because I don’t know where to re connect it up front since I took the wires out
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Old 02-17-2021, 12:08 PM   #17
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Yes, you can typically remove the safety interlocks. They're usually solenoid valves that are placed in line with a normal air system. You're going to have to get your hands dirty, do some troubleshooting, and figure out what exactly does what on your bus to get this fixed.

I'm sorry, but I'm not aware of a simple follow the steps procedure available to alleviate your troubles.

First, you need to find the safety interlock solenoid locations. Once found, remove the solenoids that are the offenders and then try to restore your air brakes back to a normal system. You can do this by tracing the air hoses from the park switch and see where they lead. One should go to the air supply, the other to the park brake relay valve.

Like I said earlier, I'm not familiar with your model of bus, so I can't help you on where those solenoids would be located. Some buses have them under the dash, others near the fuse panel.

A problem that might pop up is that some some buses use interlocks that also apply the service brakes as well as disabling the parking brake release, so that all 4 wheels are fixed during lift operation. So you might have to remove more then one solenoid to get the bus moving again.

If you're not comfortable with this, hire a competent mechanic to do the work for you. Braking systems aren't something you want to give the old college try at fixing. They're very important systems that have the ability to kill you and others if not done properly.
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Old 02-17-2021, 12:08 PM   #18
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Not to slam the barn door after the horse ran out, but it's imperative to know what wires you're removing when doing demo work. All too often people buy a bus, gut the thing thinking it's a simple system, and then find out the hard way that it's not, much like you have done.

Hopefully somebody reading this in the future will take heed and not be so cavalier at removing stuff. But truthfully, people only seem to read after they've got the system messed up, so I won't hold my breath.
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Old 02-17-2021, 04:12 PM   #19
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Thanks for all the help, I am now almost certain it is the sensor for the back lift door that got disconnected some how during demolition and then mistaken for a speaker wire when we stripped those. Should be easy enough to fix once I get a replacement wire I’ll just have to figure out which one of the plugs to plug it into above the front door.

And yes I hope someone else takes this as a warning on how easy it is to make stupid mistakes. Unfortunately I’m extra dumb because I did read up on lots of this prior to doing anything electrical and still pooped it. We were checking lights and following lines to be careful as we went and just from inexperience and perhaps a bit too much eagerness made this stupid mistake.
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Old 02-17-2021, 04:21 PM   #20
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Yep. When in doubt yank it out. Wires? Yank them out. A/C? Yank it out. Heaters? Yank them out. Defrosters? Yank them out. The first rule is do no harm. It has been put there for a reason. Try to figure out why.
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