Cant start 99 AmTran

[Big Jeff]

Our 99 AmTran 25040 quit starting, the batteries were shot and replaced it, remover the starter and had it tested and was good. Turn the key and nothing. Anyone know where to find a schematic for the ignition system?

[Njsurf73]

Originally Posted by Big Jeff

Our 99 AmTran 25040 quit starting, the batteries were shot and replaced it, remover the starter and had it tested and was good. Turn the key and nothing. Anyone know where to find a schematic for the ignition system?

Couple of questions:
Did you remove any safety stuff (door buzzers or window locks)
Have you tried jumping the starter right off the battery? Solenoid might be bad.
Small possibility that the ignition switch went bad (very small)

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[Njsurf73]

Oh and if your emergency exits have locks, they need to be unlocked.

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[Big Jeff]

Originally Posted by Njsurf73

Couple of questions:
Did you remove any safety stuff (door buzzers or window locks)
Have you tried jumping the starter right off the battery? Solenoid might be bad.
Small possibility that the ignition switch went bad (very small)

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No sir, none of the safety stuff removed. The solenoid is getting power, we are thinking maybe the ignition switch, was previously replaced before we got it.

[Njsurf73]

Originally Posted by Big Jeff

No sir, none of the safety stuff removed. The solenoid is getting power, we are thinking maybe the ignition switch, was previously replaced before we got it.

Is it powering on the dash when you turn the key?
Try jumping the starter to make sure it runs.


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[Big Jeff]

Originally Posted by Njsurf73

Is it powering on the dash when you turn the key?
Try jumping the starter to make sure it runs.


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Yes, we get power to the dash. Will try jumping the starter

[Njsurf73]

Is it a conventional?

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[Big Jeff]

yes, we bought thru a auction. It worked several times and just quit.

[Robin97396]

Do you know what the interlock system is on your bus?

[Big Jeff]

Originally Posted by Robin97396

Do you know what the interlock system is on your bus?

No sir, we have no user manual and I called and looked all over for one.

[Robin97396]

Don't feel bad. Most of us don't have manuals either.

Your bus is equipped with a safety system called an interlock system. You've noticed the switches on the back door. All the exits have this safety system that prevents the bus from starting if the top hatch or rear doors are open. The bus also won't start if the doors are locked. All exits have to be unlocked, but closed, to start the bus.
Several times a week somebody snips the wires off of those safety switches, then their bus won't start. Most of the time you'll hear a buzzing when you turn the key, but sometimes there is no buzzer.

The interlock system won't let you start the bus if any of the safety switches are not in the right position. The dash lights come on but the starter won't turn. It sounded like that was what happened to you, but that's just a first guess.

You can disable the interlock system but there is no set method for all buses. There are a number of videos showing how to disable the interlock system. They may or may not be similar to your bus, but they will give you a general idea of how to disable the interlock system.

The first thing you can do is make sure your rear doors and the top hatch are unlocked but latched. If you've opened the top hatch at some point you'll need to reconnect it properly before you'll be able to start the bus.

Honestly I haven't disabled the interlock system on my own bus. I'm pretty bad at electrical work. I've stripped out the interior and spray foamed the walls and ceiling without interrupting the interlock system.

If you've already been able to start your bus, disregard everything I said.

[Big Jeff]

Originally Posted by Robin97396

Do you know what the interlock system is on your bus?

Does it have a PNR switch in the system?

[Robin97396]

I don't know that the PNR switch is. I have a feeling this is going to be today's learning moment.
Several times a week someone has problems with the interlock system. It's a safety system that keeps you from starting the bus if a kid has a door open. Each door has to be latched but not locked before the bus will start. That includes the top hatch needing to be latched properly. If any of those door switches are not in the proper position the starter will not engage. If any of the wires have been cut or damaged the bus won't start. This is always my first guess when someone says their bus won't start.

Ok, your turn. What's a PNR switch?

[Big Jeff]

Originally Posted by Robin97396

I don't know that the PNR switch is. I have a feeling this is going to be today's learning moment.
Several times a week someone has problems with the interlock system. It's a safety system that keeps you from starting the bus if a kid has a door open. Each door has to be latched but not locked before the bus will start. That includes the top hatch needing to be latched properly. If any of those door switches are not in the proper position the starter will not engage. If any of the wires have been cut or damaged the bus won't start. This is always my first guess when someone says their bus won't start.

Ok, your turn. What's a PNR switch?

Park-Neutral-Reverse

I had to take the Stop sign off, would that be part of the interlock system? It would be a nice to have a schematic or a manual to troubleshoot . We don't have any door locks on it, Ill check the top hatches. Thanks

[Njsurf73]

Originally Posted by Big Jeff

Park-Neutral-Reverse

I had to take the Stop sign off, would that be part of the interlock system? It would be a nice to have a schematic or a manual to troubleshoot . We don't have any door locks on it, Ill check the top hatches. Thanks

From any schematic I have seen, the interlock is a solenoid (in most cases) that has a wire to a remote ground. If you disconnect the remote ground and ground it to the chassis it should effectively disable the system.
Check in the wiring box below the driver window.

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[Big Jeff]

One of our mechanics ran a wire from ignition straight to starter and we can now get it to turn. It just wont fire, does the interlock system also shut the fuel off?

[Robin97396]

Not being a bus mechanic, I'd guess that could easily be a part of the interlock system.

That's another vote for a mechanical fuel shut off valve instead of electric.

[Njsurf73]

Crack an injector and see if fuel is making it up there.

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[Robin97396]

If they can crank the engine, but it doesn't start, it's not getting fuel.

[Njsurf73]

Originally Posted by Robin97396

If they can crank the engine, but it doesn't start, it's not getting fuel.

Yeah. I forget sometimes... No spark. Just fuel and compression.

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