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Old 02-23-2015, 01:07 PM   #1
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Exclamation Kill Switch Disengage - NEW

Hey World of Skoolie.net!

So, my girlfriend and I are converting a 30 foot 1995 Thomas bus to be our home. We are very excited and aware of what lies ahead. It feels amazing to know that this community is here to help us get through the tough parts.

We ran into our first problem (which I'm sure is very common) when we were removing the jungle of wires. I've searched this thread endlessly and haven't found the proper solution for our situation.

We removed all of the speaker, interior light and door alarm wiring. We have 4 exits, not including the front door. So, not only did we clip the wires to the "kill switches" but we removed them as far as we can tell. Now the bus will not start and there is the emergency buzzer. I'm not sure if completing the circuit is an option for us as the wiring has been lost in the madness.

Is there a way to remedy this without "completing the circuit". The bus ran perfectly fine before this process so I'm assuming this is the issue.

Any ideas would be greatly appreciated!!
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Old 02-23-2015, 03:22 PM   #2
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If your switches for the emergency exits have four wires, which I'm sure yours do, then you have an ignition lock. Its a safety feature due to being a school bus.
I suck with electricity, but if no one comes along with the info you need, I'll get ahold of someone I know for you.
My electrician friend tells me these buses are as easy as it gets for vehicle wiring, so it shouldn't be a bit deal to fix it at all.
You should post an introduction in the new members section so we can get to know you and your bus better.
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Old 02-23-2015, 06:51 PM   #3
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It can be done up front either under the dash or in the side electrical box. I can't say much more than that without seeing either the bus or a wiring diagram. Best bet would be to find an old guy who has worked on cars forever.
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Old 02-23-2015, 09:51 PM   #4
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Smile kill switch

On my bus the exit doors have switches that disable the starter and you
naturally assume the are set up normally open contacts but they are actually
normally closed, which means when the door is closed the contacts are closed completing the circuit allowing the starter circuit. So by removing all the wires to the switches you now have an open circuit to the starter interlock. What you will need to do is find the interlock relay and bypass the switch circuits this is fairly easy with one switch but it appears that you have multiple switch removed. If you have a door switch with wires still attached you can test the switch to see which wires have continuity with the switch button depressed as with the door closed. This shows you the color of the wires you need to deal with as in connect together to bypass the switches.
You might also get lucky and find a number on the wires, printed vertical/
horizontal which gives you a better way of tracing your problem circuit. Once the two wires are identified you connect them together and your done. The connection should be made as close to the interlock relay so that you eliminate all of the switches in the system.
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Old 02-25-2015, 04:58 PM   #5
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4 Wires

Quote:
Originally Posted by EastCoastCB View Post
If your switches for the emergency exits have four wires, which I'm sure yours do, then you have an ignition lock. Its a safety feature due to being a school bus.
I suck with electricity, but if no one comes along with the info you need, I'll get ahold of someone I know for you.
My electrician friend tells me these buses are as easy as it gets for vehicle wiring, so it shouldn't be a bit deal to fix it at all.
You should post an introduction in the new members section so we can get to know you and your bus better.
Hey,

Thanks for the response.

yes, the exits do have 4 wires. I'm wondering if I can trace them all the way back to the source and just unplug them? Or does the circuit need to be complete.

Also, put of a hello in the welcome page! Thanks for the advice
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Old 02-25-2015, 05:29 PM   #6
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Your Cummins is still mechanical.

I like all the advice you have been given, but I would start from the other end to avoid getting lost in the mess of wires.

Start at your starter. There will be a solenoid on the side of it with two or three wires. One will be the big cable running to the battery's. The others are from the ignition switch. You may have one more solenoid between the ignition switch and the big starter solenoid.

What your doing is rewiring your starter circuit.

Most of the older mechanical buses starting circuits are the same as a mid 80's ford truck. Key ignition switch needs a constant 12 volts to one side, turning it activates the big solenoid. The big solenoid has three wire connections and also needs constant 12 volts to one of the big connections. The little power wire from the ignition switch activates the solenoid, sending power to the 3rd connection on the solenoid. That third connection sends power to the solenoid on the starter.

They do this because the ignition switch can't handle the massive power draw the starter needs. The solenoids are really relays. They used the one in between the key and the starter as a fail safe.

You can start your bus with any metal object. Simply arc the power from the big cable lug on the stater solenoid to the small one. This will engage your starter and spin your engine.

Please be care full starting your bus this way. Make sure to stay safe.

This simplicity is why mechanical buses are better for conversions. This is also why I removed the entire wiring harness from my bus, and I'm starting from scratch.

Nat
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Old 01-27-2016, 02:16 PM   #7
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My husband and I have this same problem where our mini bus will not start because of the safety feature having to do with the emergency exit doors. We found there is power to those switches, but no power to the starter. We have removed all the seats in the bus and use the bus to transport clothing for a homeless ministry. We just want to get our bus going. Thought maybe we could disable this safety feature. Any help would be greatly appreciated!
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Old 01-27-2016, 02:36 PM   #8
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You don't say what kind of bus. Simple answer is connect a wire from ign switch to starter solenoid. If you have automatic transmission, wire so neutral safety switch is between switch and starter.
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Old 01-27-2016, 03:11 PM   #9
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Sorry about that! It is a 2003 GMC bus Thomas Built, gas engine if that makes a difference. I am not mechanical at all!
Would your answer still work given that bus info I just gave you?

Quote:
Originally Posted by somewhereinusa View Post
You don't say what kind of bus. Simple answer is connect a wire from ign switch to starter solenoid. If you have automatic transmission, wire so neutral safety switch is between switch and starter.
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Old 01-27-2016, 03:19 PM   #10
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Works for anything automotive. This is the BASIC starter circuit. Since yours is new enough for electronic stuff other things may be involved. Turn the key to on, run a wire from bat+ and small wire on starter to see if it will start.
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