Removing unused wires from multiplex electrical in Thomas C2 2008

[RoundEartherz]

Hi all!

We are converting our first skoolie: 2008 Thomas Saf T Liner C2 - handicap short bus and are very excited! We know the wiring on this bus is quite complicated but we have been learning and ready to tackle this head on despite not being automotive electricians. Lol. We would like to remove unused wires but not sure at what point in the circuit can we remove them without getting into trouble. We are in the process of getting the complete wiring schematics from Freightliner/Thomas using our VIN. We want to get rid of both wires (live and ground) from the appliance/load (ex: interior dome lights) to the module (computer system) and from the switch to the module. Will this cause our system to go bonkers? We already tried removing the wires from the switch to the SHM (switch hub module) for lights we don't need (mostly school bus related) but we get an error message on the dash display (Fault code indicates it's a missing smart switch - which makes sense.) Bus works perfectly fine even with this error message so is there any way to get rid of this error message or is this just something we will have to deal with if we want to remove the switch wires?

Any help and guidance would be appreciated! Thanks in advance.

[Oldyeller]

Before you get too excited about removing 'un-needed' wiring from your bus, spend some time searching on this forum for threads in which folks have ended up with no start situations because THEY removed un-needed wiring, there are a lot of them.

I'm in my 3rd summer of my conversion and I haven't removed any wires and I don't plan to unless/ until I have to or until everything else is done necessary to get me on the road.

If you absolutely, positively can't resist dewiring, make sure you only do one wire/ circuit at a time so when you end up in a no start situation, you'll know there was only one change to reverse.

[RoundEartherz]

Thanks for such a quick reply!

Do you think that the unused wires could be a fire hazard? Or even that they will be just in the way when we build out our ceiling and walls? I guess I would be worried that I didn't stop the circuit correctly and then I have a live wire in the bus next to all the insulation. Eep!

And for sure, we will definitely only do one de-wiring at a time if we go that route.

[dbsoundman]

Yeah, just don’t bother. If the wire is properly capped wherever it was cut (say, where it used to connect to a door alarm switch), there’s no fire hazard.

[DeMac]

I left all of mine. I'm silly. Label everything using a "Wire Marker Booklet" as you go.

Please update this thread if you experience buzzers/alarms, overnight battery depletion, or especially if your bus won't start or bus starts but won't drive.


Also, Welcome to the Insane Asylum!

[Oldyeller]

Originally Posted by RoundEartherz

Thanks for such a quick reply!

Do you think that the unused wires could be a fire hazard? Or even that they will be just in the way when we build out our ceiling and walls? I guess I would be worried that I didn't stop the circuit correctly and then I have a live wire in the bus next to all the insulation. Eep!

And for sure, we will definitely only do one de-wiring at a time if we go that route.

If someone went through your interior wiring harness cutting wires willy-nilly the possibility of a short circuit is there. If all the wires are terminated in proper connectors or were properly capped off if cut then the possibility of short circuit is probably not high. For the most part the interior wiring should be fuse protected, if a short occurs a fuse should blow.

Sorry, forgot the 'get in the way part'. Hard to tell but it depends upon what you're going to do for an interior. Not sure about your bus but mine has a seat rail along the bottom of each side wall that makes a ledge. It stays put, it's part of the structure of the bus. My wiring harness will sit on that ledge/rail until I decide it's time to risk universal armageddon by pulling it apart to remove/repurpose individual circuits. It is my hope that I can repurpose some of it for lighting but I really have no idea yet - what I'm going to do for lighting, how much load unused circuits might be able to handle, blah, blah, blah.

[ewo1]

Originally Posted by RoundEartherz

Thanks for such a quick reply!

Do you think that the unused wires could be a fire hazard? Or even that they will be just in the way when we build out our ceiling and walls? I guess I would be worried that I didn't stop the circuit correctly and then I have a live wire in the bus next to all the insulation. Eep!

And for sure, we will definitely only do one de-wiring at a time if we go that route.

Busses already have live wires next to insulation, so don’t worry about that too much.

A way to play it safer, remove the fuses/circuit breakers to the circuits not needed that way there will be no power in those circuits.

Another helpful thing to do, create a diagram inside a bus block diagram that shows where the cable runs are then add in the wires you run. That way, later in the distant future when memory begins to fil, you will know exactly where all the cable/ wire runs are.

International/ Amtran has this in the service manual and I found it very useful!

Take. Look -> HERE

[Meathead]

Someone pointed out two things to me.

1) Anything connected to the Welden flasher board is not needed. You can disconnect.

2) The wires that you disconnect can be used later if you leave them in. Many of them run front to back bcuz they are flasher wires.

As I was finishing up my trim work inside my bus I realized that my reverse beeper didn’t work. Then I realized that my reverse lights were out as well. I traced wires every which way and determined that my problem was continuity in the wire from front to back. I probably put a nail thru it. I never found exactly where bcuz I used one of the flasher wires to go around the bad spot.

Thanks to whoever posted that tip!
[emoji3522]Dave

[RoundEartherz]

Thanks to all for great suggestions! I think cutting off the circuit at the fuse level sounds like a great idea, and possibly leaving flasher wiring to rewire as necessary in the future is great, and drawing a diagram!

Some of our interior dome lights were replaced from original and whoever did it did not use connectors and instead just soldered the wires and heat shrink wrapped it so we had to cut those to remove the lights...Would love to cap them properly or remove those wires - or find the fuse and disconnect that circuit.

And in some bummer news, Freightliner denied our request so it looks like we will NOT be getting those wiring schematics. We submitted an application online as a vehicle owner so that we could get access to their service/workshop manuals and wiring schematics. They denied our request on grounds that the warranty wasn't in our name. I will try calling the closest dealership tomorrow and see if we can still gain access to the schematics somehow.

Thanks everyone! Will put up any updates if we crash and burn.

[ewo1]

Originally Posted by RoundEartherz

.

And in some bummer news, Freightliner denied our request so it looks like we will NOT be getting those wiring schematics. We submitted an application online as a vehicle owner so that we could get access to their service/workshop manuals and wiring schematics. They denied our request on grounds that the warranty wasn't in our name. I will try calling the closest dealership tomorrow and see if we can still gain access to the schematics somehow.

Thanks everyone! Will put up any updates if we crash and burn.

You went in the wrong direction for the wiring diagrams.
Try calling a Thomas bus dealer instead. They will need the vin number. Call them as start by asking for one specific wiring diagram and then twist the conversation and ask for a couple more.

I have found Thomas bus dealers very helpful in the past !

I sent you a pm with contact info for the Thomas dealer who has been very helpful in the past .

[cadillackid]

Originally Posted by Meathead

Someone pointed out two things to me.

1) Anything connected to the Welden flasher board is not needed. You can disconnect.

2) The wires that you disconnect can be used later if you leave them in. Many of them run front to back bcuz they are flasher wires.

As I was finishing up my trim work inside my bus I realized that my reverse beeper didn’t work. Then I realized that my reverse lights were out as well. I traced wires every which way and determined that my problem was continuity in the wire from front to back. I probably put a nail thru it. I never found exactly where bcuz I used one of the flasher wires to go around the bad spot.

Thanks to whoever posted that tip!
[emoji3522]Dave

I evewn left mine connected ot the weldon device for convenience they dont get against something the shouldnt.. plus they are labelled.. so when I wantto use one (and I have) its easy to know which is which.. I disconnected the power and ground and the dash switch wires to the weldon so I couldnt accidentilly turn it on..

[HamSkoolie]

I'm experienced with aircraft and automotive wiring and schematics. I have removed ALL of the school bus specific wiring ..... child behind, camera, overhead hatch alarms, rear escape window alarm, some IC board device with lots of wires attached, half a dozen coils of cables attached to those bus systems and more. I also removed all the dome light and speaker circuits to the actual lights and speakers which keeping the main line on the left side from front to rear. All the AC power and control circuits as well as the AC refrigerant lines were also removed (255 feet of 7 conductor cable and 300 feet of refrigerant lines) along with the factory head knocker AC units that only function with the engine running. All three heaters and their control cables were removed from the interior as well while the coolant lines were maintained due to their need for dash heat and defrost.

When all was said and done, the entire right side harness from the right rear corner forward was removed and replaced with two wires run from the left side harness. One for the Right over front wheel turn signal and another for the Right midships clearance lamp. Once the speaker and dome light circuits were removed those were the only remaining circuits in service (and the turn signal wire was actually missing from a connector at the Right Rear corner forward (didn't even have a pin in the connector).
I've kept a few of the circuits that are no longer needed. They will provide a switchable (red) lighting that can be controlled from the drivers seat in case a passenger needs to move about the cabin while under way.
now have a streamlined electrical harness on the Left that will need less that 1/2 the space the OEM harness needed and no harness of the Right.
As the build progresses, necessary circuitry will be added but will be powered from the house batteries on a 24 volt (fused) main supply feeding 24-12 volt buck converters that in turn supply regional fuse boxes. The reason for the 24 volt main supply is reduction in line losses and shorter fused 12 volt circuits to the USB chargers, lights, fans, pumps, and other 12 volt devices.
110/120 will also be run but the topic at hand is removing wires.
I've pulled hundreds of feet of wires weighing I would guess 200 or more pounds when you count all the AC cables and individual wires. I'm keeping all of them and will do a video on the YouTube channel about what was pulled and weigh them to get an accurate figure.
Our build however is going to have distinctly separate "chassis" and "house" DC circuitry so that the chassis batteries can be isolated when parked. They'll be able to be charged from the house system with a charger incorporated into the battery bay and may end up with a trickle charger depending on how the system operates in real world conditions once we're on the road.