Simplifying the bus wiring

[Fred Mc]

As I worked thru a miriad of electrical problems and pouring over the electrical diagrams it occured to me that a lot of the fail safe features on a bus aren't necessary for bus nuts and as these buses are old to start with, and getting older, they just present an opportunity for more problems.

A good example is the start feature that prevents the starter from being engaged once the bus is running. Most, if not all cars (excepting push button starting on the new cars) didn't have this feature and we all seemed to get along fine without it. But the added wiring/relays etc.,is  just another place for a problem to occur.

Maybe the "kiss" principle could apply here.

Some guys like gumpy have done a remarkable job but they basically started with an empty shell. Has anyone eliminated any number of circuits, relays, etc, on their bus.

Regards
Fred

[gg04]

We've only built 4 buses and we have completely stripped and replaced all wiring and relays . Using only one's needed not redundancy ..rdw

[silversport]

On my 1962-GM-4106 not only was the original wiring had most of the color coding worn off, there was so much additional wire and circuits added that I could not make heads or tails of the mess. I pulled out every wire harness installing new wiring, breakers, and relays with 12 extra 12 gauge wires for future needs. Following the original schismatic put back what was need plus adding a key ignition and head light switch .       

[Fred Mc]

Where did you run the wiring. I can't use the original runs as the bus is already converted.

[bevans6]

I took out the starter interlock and the engine shut-down system.  It had already been disconnected anyway, I reused the relay as my neutral relay with my automatic transmission.

[brmax]

I can see this post being very interesting and a need for lots of note taking.
The keep it simple strategy is a great lead in and could go towards categories.  Possibly in any build stage the need for some routes and or means to carry the wires, in whatever priority levels.  These runs, carriers and priorites can really benefit here in the post with some of the experienced that are in the forum. Just sayin Thanks

Good day there
Floyd

[bevans6]

Discussion:  The starter interlock in an MCI type of system is based on fuel pressure.  It provides a ground to the start relay, which is located inside the engine bay electrical cabinet.  The start relay is what switches the starter solenoid on, so without the ground the starter can't be turned on.  Issues - if you use an external priming pump you can get enough pressure past the mechanical fuel pump to trigger the pressure switch.  The pressure switch itself can obviously fail, and the wiring can get old and a termination can fail.  There's nothing wrong with having a fuel pressure interlock to disable the starter motor, but it introduces several failure points and the vast majority of vehicles get along without one.

Emergency engine stop systems.  These work on the basis of a number of sensors - in the MCI world there would be two engine hot sensors, one in each thermostat housing, one low oil pressure sensor, maybe a low coolant sensor as well.  All of these sensors would be wired to dash tell-tales and the same buzzer as the low air pressure buzzer, so you would have audible and visual warning indicators on the dash.  The engine shut-down relay adds an automatic engine-off to the deal.  I personally would rather the option of making my own decision to continue to drive to a safe place, rather than a forced engine shutdown in a dangerous place.  You can disable the engine shutdown relay (which is an optional extra anyway) and retain the buzzer and dash tell-tales.

Do either of these things eliminate a lot of wiring?  Not really.  One ground wire that runs from the engine bay panel over to the fuel filters, one relay and a few wires completely inside the engine bay panel, that's the extent of it.  As I mentioned I re-purposed my engine stop relay to be my neutral relay, but all the rest of it is still hooked up. 

Brian

[gg04]

It's more age and condition. Ran 2" nonmetallic conduit down drivers side interior floor originally. When changed to ddec  1"nonmetallic through bays to feed accelerator and warning lights.

[GiddyInn]

I am giving serious thought to this. Right know the start function doesn't work on either end, nor does the shut down system. The ac had no pressure and is being removed to provide generator room, the headlight system is sketchy, and there was a ton of wires to the overhead storage that needs to be removed. Trying to decide if I should just start over and keep it simple.

[bevans6]

When I remove a stock bus system, I try very hard to remove the wiring (and air systems) tied to it, back to the electrical panel.  That tends to leave me with unused wires that I can re-purpose.  I just finished re-purposing the emergency shut-down air flap system wiring on my bus.  I replaced the push-button switch with a toggle, and used the wiring for an electric priming pump.  When I started the engine this time, I flipped the switch and pumped for five minutes to fill the strainer filter and put pressure up to the mechanical pump, cranked the engine a few times to fill the secondary filter and away she went.  When I install a transmission temp and pressure gauge, I'll use spare or repurposed wires from the rear engine bay panel to the front electrical panel.  I also pulled out the old OTR air conditioner and and pulled wires into the pressure line from the condenser bay, using the pressure line as conduit.  Lots of ways to pull in new wiring, but the old wiring is a great resource and I wouldn't just pull it out willy-nilly.  On my MCI every single wire has a metallic tag with a circuit number on the termination, so you know exactly what wire you are dealing with, and where it goes.

[MB LeMirage]

Has anyone ever done one of those Painless Wiring Systems from scratch on a bus and just said to Heckla with the original mess of commercial redundancy and headache built into the original system. We have used them on some hotrod stuff and they sure make it easy and well ...painless.
Ryan.

[brmax]

Painless eh!
Must be a big bottle of tylenol in that order 
I have seen some builds where the owner has did it all and it was impressive.

Floyd

[Fred Mc]

Brian

Did you leave the wiring in place that connects the drivers electrical panel to the  main electrical panel in the back or remove that as well. I was wondering if you could just clean up the panels and go from there the 50 or 60 runs woul come in handy I'm concerned that those circuits might have damage/corrosion in hidden areas

[bevans6]

I clean up the inputs to the panels, and leave the panels and the base wiring alone.  I feel the core systems are great, so just clean up the exterior of the wiring, if that makes sense.

[Fred Mc]

Thx Brian

Yes, it makes sense and is encouaging.

Regards

Fred