Triple Function Switch

[paul102a3]

Anyone ever had to replace the triple function switch in the rear junction box on an MCI?

Mine is acting up and I don't know if it is a bad ground or the switch itself.

Clearly, the switch controls three functions but what three? I just know that once in a while, I have to jiggle the wires that go into the switch before the starter motor will turn over.

Paul

[Melbo]

Paul

I have owned my MC8 for over 4 years and I have NEVER used the switches in the box at the back of my bus

I know they do something -- I have rewired and / or replaced some of them because they looked old and damaged.

I have wired stuff in the box behind the switches for the tail and brake lights and back up camera but I have never used the switches.

Just my experience.

Melbo

[JackConrad]

Paul,
   On our MC-8, there is a switch to turn the engine compartment service lights on & off, a switch that selects Front Start-Off-Rear Start (the rear start position is momentary) and an engine run on/off switch as well as a momentary Emergency Stop push button switch.  Jack

[bevans6]

On mine, the switches are the same as Jack's.  The only "triple function" switch is the front start/rear start/ start switch.  To use it, you first turn the batteries on, place the dash switch in the Run position, go around to the back of the bus, place the triple switch in the rear start (middle) position, then you can start the bus by pressing it down into the momentary on position.  Starter motor works, engine starts, you release it to the middle position (rear start) or to the top position (front start) depending on what you plan to do next.  If you leave it in rear start, the front start button doesn't  work, which would shock and amaze you the next time you tried to start the bus if you forgot...

Hope this is what you were looking for.

Brian

[paul102a3]

Sorry everyone! I did not write the question very well at all.

The rear junction box in my bus is located right behind the tag wheel well. Inside this junction box is a switch called the "triple function switch". This switch has something to do with the safety systems within the electrical system of the bus and engine.

I was working inside the junction box last week tracing the wiring to the trailer plug outlet so we could tow a toad.

When I started the bus and it aired up, the "not gen" and "Start ?" lights stay on. Not good!

I pulled the cover off the junction box and wiggled some wires and low and behold everything was good to go. I shut the bus off, put the cover back on the junction box and the starter would not engage. Pulled the cover off, wiggled some more wires and the bus started. Shut the bus off, starter would not engage. Repeated the wire wiggle and the bus started.

After many wiggles, I have traced the problem to the wires entering this "triple function switch". A call to MCI says the switch is no longer available but they say there is some kind of kit that will replace the switch.

I guess my real question should have been has anyone had to replace the switch and does anyone know the exact functions of the switch.

The folks at our local MCI facility would have to research the switch and functions but I thought I would ask here first.

BTW, the switch is only accessable by removing the air filter housing so it is not easy to diagnose.

Based on my experience so far, I am guessing a bad ground within the switch so I will start there.

Paul