Jimbo_Slice

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Burien
Working on a friend's bus, 09 International CE200, maxxforce 7, air brakes, we had a no-start issue that we fixed, turned out to be the IMS attached to the starter, but in the process of trying to figure out why it wouldn't start, we ended up replacing the air dryer cartridge and one of the brake chambers thinking it might be a parking brake interlock preventing it from starting. We also, while we were doing that, removed the stop arm, since this is a conversion, and the electronics for the doors, but it doesn't throw a code about the doors without them, so I don't think the doors are our problem with the brakes, it starts up fine.
Full 120 in both tanks, but the dash control valve for the parking brake (big yellow knob) doesn't get any pressure, no air noises, no tactical feedback. Brakes, as the title stated, don't release. Even started it up with the hoses disconnected and it still built up full 120psi in both tanks, no air going to the dash control valve.
Got a spn (I think those are the letters?) 3975 fmi5 code which, best I could figure out points to stop arm. I'm not 100% I found the right place to look up that code, but we did remove the stop arm and the light that comes on on the dash is an abs light, so I'm thinking maybe removing the stop arm tripped something that won't let air get to the dash control valve, and that's why the brakes won't release. I tried to disconnect the positive terminals from the batteries and jumper the wires that would have gone to the stop arm (there were 3 wires, I tried all possible jumper configurations, disconnecting battery and waiting 15m between) but zero change in the codes and no new codes, nothing. I'm running out of ideas and tired of bashing my head against the wall and I know we should have messed with this one thing at a time rather than fiddling with multiple things and needing to figure out which one broke it, but I honestly been working on cars my whole life and had no idea how busses worked when I started this whole journey and I walked into it with other people had already started pulling some of the stuff apart and I've tried to dig myself outta this and I think it's time to throw myself on the mercy of the court and seek some salvation. Anyone have any hints about what is going on with this parking brake?
 
Working on a friend's bus, 09 International CE200, maxxforce 7, air brakes,.....

. We also, while we were doing that, removed the stop arm, since this is a conversion, and the electronics for the doors, but it doesn't throw a code about the doors without them, so I don't think the doors are our problem with the brakes, it starts up fine.
What exactly do you mean by this?
What did you do and to what doors?

e-exit?
wheelchair lift ?


The E-exit and for sure the wheelchair lift, if you removed the "switches" that would trigger the TCM to apply the brakes because the TCM thinks the doors are open, creating a safety issue. That would be the first place i would look since you messed with the door electronics as you say.

The easiest fix would be, find the 2 wires that go to the interrupt and splice them together so the TCM thinks the doors are closed.

also, on my '05 Amtran with a wheelchair lift, in order to release the parking brake i have to press down firmly on the foot brake in order to release the parking brake.
you might give that a try.
If there is only one wire then that one wire is looking for a ground.

Your issue is electrical, don't look further into other systems.
your not the first guy to go thru this!
 

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So I
What exactly do you mean by this?
What did you do and to what doors?

e-exit?
wheelchair lift ?


The E-exit and for sure the wheelchair lift, if you removed the "switches" that would trigger the TCM to apply the brakes because the TCM thinks the doors are open, creating a safety issue. That would be the first place i would look since you messed with the door electronics as you say.

The easiest fix would be, find the 2 wires that go to the interrupt and splice them together so the TCM thinks the doors are closed.

also, on my '05 Amtran with a wheelchair lift, in order to release the parking brake i have to press down firmly on the foot brake in order to release the parking brake.
you might give that a try.
If there is only one wire then that one wire is looking for a ground.

Your issue is electrical, don't look further into other systems.
your not the first guy to go thru this!
So I agree that door interlocks seem the first point of focus, but we tried jumping the first connector a couple ways, and it either did nothing or lit up a dash light if it was jumped the right way, and not jumpering anything was the way that let us start the bus, so I think the switch for the first door in series might have been normally open(or whichever means it doesn't connect when the door is closed)
 
ok, try to be more specific. Your speaking in general terms.

What door?
what connectors?
what dash light you talking about?

did you try stepping on the brake pedal, while holding it down, release the parking brake?

In order to help you you need to be more specific.
you didn't download the wiring diagram I posted?
 
ok, try to be more specific. Your speaking in general terms.

What door?
what connectors?
what dash light you talking about?

did you try stepping on the brake pedal, while holding it down, release the parking brake?

In order to help you you need to be more specific.
you didn't download the wiring diagram I posted?
There are three doors, one at the back, one on each side. I'm not sure if the passenger side used to have a lift, but I know it currently doesn't not. The first door in series in the wiring, as far as I can tell, is the passenger side door, its switch had several (I think four) wires going to it, the rear door had one fewer, and the driver side emergency door had just two. I'll double check these connections, but last we'd messed with jumpering them, there was no error light on the dash without anything connected, but if we added a jumper to some of the wires, we did get an indicator light. I'll be heading over to do some work there tomorrow, so maybe I'll just mess with jumpers there and see if I can get get some satisfaction while I'm there, as you said. I think if I do find success with jumpers and that solves the problem, I'll just chase the wires back to the front and wire nut those two wires together somewhere neat and tidy and remove all the unnecessary wiring beyond that point.

Edit to add: while we were messing with the door connections, we were mostly trying to figure out what was preventing the bus from starting, so I think I'd kinda just filed that away as solved and basically forgot about it potentially being an issue once I got the starter wired up and the engine firing, so it's totally possible I was just looking at everything else and had just assumed that was sorted.
 
The wiring diagram I remember looking at had a white ground wire running through the passenger door switch and then to the rear handicap door. When the ground was lost, the valve in the dash prevented the parking brake release. That was on a bus with hydraulic service brakes but still may apply here.
 

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