Hey guys... I've been gutting my bus overhead bays, ducting along walls, etc. No welding (I'm familiar with cutting all power first if I had been). I've cut off a lot of wiring along the way, but only the wiring in the upper luggage bays that lead to the lights, speakers, etc.
I fired up the bus today, since I haven't ran it for a couple of weeks.
It started ok, but there is a light on the dash that says "Network Failure" (and wheelchair door open. I'm still trying to figure out how to bypass the safety stuff there). The bus starts ok, but now the fast idle won't work, the fuel pedal doesn't do anything. I don't have any kind of manual or wiring diagram. I've been in contact with MCI to order a manual, but to no avail. Is it possible that I fried the network somehow? Again, the main shut off has been off, and I have done no welding.
I suppose I should have researched the wiring better before removing the upper bays, but I have the power supply disconnected that feeds everything in the bays, and it is all pretty easy to see that it doesn't go to anything with the engine controls. Thanks all! Glennman
I have no firsthand experience, but I do remember reading about others who have had issues with weird things happening when they removed the overhead bins and the associated wiring.
Maybe do a thread search to find out what the solution was in those situations.
Yep you have cut a wire going to something that is a interlock,will the shift pad shift ?
You might have wires running through the overhead bays that are important. I chopped off the wires in my overhead bays as I thought they all went to the non-working HVAC control panel in the back, but I found out I also cut the wire for the marker lights in the rear. That was an easy fix.
Quote from: luvrbus on October 03, 2020, 06:09:33 PM
Yep you have cut a wire going to something that is a interlock,will the shift pad shift ?
Nope, that too. The shift pad will not shift, the fuel pedal does nothing. Could it be a safety thing that prevents the operation of the bus because it thinks the wheelchair door is open?
Welcome to the madness! Those buses were a known headache to mechanics from day one with all their crazy CAN systems and multiplex computer systems.
But yes somewhere you have cut a wire that is indicating something is wrong.
It may or may not be the wheel chair door sensor, or something totally different that just shares that warning circuit.
I'd start AT the sensor for the wheel chair door and trace the wires back toward where ever they go from there. If you find one cut splice it, if not your in for a long fun ride to find what you did cut.
Another idea to reconnect wires you cut one by one until you get the one that fixes the problem.
;D BK ;D
The wheel chair interlock is programed through the transmission so you cut the wires they come up from the rear on the passengers side through the overhead baggage .You may need to go the MCI page on F/B to get the wiring schematics for the ramp I gave Yvan all of mine,MCI download manuals are not that great
Go to Harbor Freight and buy a Cen Tech cable tracker; less than 25 bucks. Will be invaluable to sort it out. really easy to use and pinpoint cut circuits.
One thing I didn't do was hack and slash all the wires. I did cut some, obviously, but for the most part, I unplugged most of them and the ones that come out of hidden places (ceiling/floor) are still hanging there with the plugs on the ends. I did cut some after those plugs that are within the bays. I still have all the wires too. I suppose some backtracking is in order. I've been watching Yvan's videos lately. Maybe I can comment on one of them to get his attention, or look for him on Facebook. Thanks everyone!
There are a couple of MCI employees on Yvan's F/B page that will answer you also they are sharp on MCI's D model
Quote from: luvrbus on October 04, 2020, 09:25:03 AM
There are a couple of MCI employees on Yvan's F/B page that will answer you also they are sharp on MCI's D model
Sounds great luvrbus! I'll see if I can find their page. Shouldn't be too hard. I just today finished (for the most part) taking down the rest of the upper bays. I'm paying a little closer attention to the wiring (a little late I suppose!).
The schematics for your coach are available online at mcicoach.com
What unit number is your coach ?
I'm guessing that there was a multiplex module in one of the luggage racks and you cut the bus wires to it and took down the main bus. The module might have been used to control lighting or the A/V system.
If you cut the multiplex bus wires, they need to be terminated, usually with a 120 ohm resistor. Or you may need to reconnect the computer so it can communicate with the rest of the bus.
It should be fairly easy to figure out. The wiring schematic from mcicoach.com should give you the colors of the multiplex bus wires. You can then go check the wires you've cut to see if any of them were the bus wires.
This should be the schematic for your coach.
Correction: I don't think your coach has the Multiplex system.
I looked at the schematics for a 2000-2003 MCI D4500.
The only network I see is the J1939 that goes between the ECM, transmission controller and driver's station.
Bus wires are usually twisted pairs. Did you cut any twisted paired wires ?
What transmission does your bus have ? Autoshift ?
Quote from: someguy on October 04, 2020, 06:56:06 PM
I looked at the schematics for a 2000-2003 MCI D4500.
The only network I see is the J1939 that goes between the ECM, transmission controller and driver's station.
Bus wires are usually twisted pairs. Did you cut any twisted paired wires ?
What transmission does your bus have ? Autoshift ?
Thank you someguy... I'll check out those links to the schematics. My bus has the Allison 6 speed, but I don't know what model (B500?). I haven't had it very long, so I'm still learning about it. It has the square impression pad with D N R and some arrows. You have to push the brake all the way down to go from N to D. Of course now, it won't do that. I don't recall cutting "pairs" of wires. I still have most of the harnesses with the large round 20 (or so) pins inside.
What do you mean by terminating all the way? That sure sounds good! Also, I don't believe my bus has the "Gold Bricks". Is that what you refer to as a Multiplex system?
Too many questions I suppose. I'll be looking at the harnesses I have and see what they look like. Thanks for all your help!
I didn't see a schematic for the Allison. Must be in the main schematic and they didn't break it out.
"Multiplex" refers to the Vansco Multiplex system that connects modules with a CAN bus. Yours doesn't have that. The Gold Bricks are just relays with some logic in them, as far as I know. I don't see any other networks in the schematic, so that supports my statement.
All network wires are twisted pairs. If you didn't cut any twisted pairs (go back and look at the remaining wires) then the non start might be coincidental. Did you touch any wiring other than in the overhead storage since you last started the bus ?
The Can Bus is a multinode bus. It can have many CAN Bus devices on it. In order to prevent signal reflection on the Bus, every CAN Bus receiver node has an impedence of 120 ohms, to sink the energy that might otherwise cause a reflection. So if you cut the CANBus twisted pair wiring somewhere and remove a node, you need to put a 120 ohm resistor across the cut wires to prevent reflections a the end of the Bus.
What module type devices were in the overhead luggage racks ? Does your bus have a fan module or A/C in the overhead bays ?
Do you get any error messages on the Allison transmission controller ? I'm guessing you would see U0100, U0400 or U0404 on it.
============================================================================================
When the control unit recognizes an error of control, the corresponding error code is stored in memory. To save there are 5 memory cells, the contents of which can be read through the display switch gear. Cells have names from "d1" to "d5".
Stop the car to read the codes. Ignition must be on!
· Read on button switch: Both buttons ↑ ↓ at the same time hold - With engine running 1 time; With the engine running 2 times.
· Reading on lever switch: Press the button menu - With the engine stopped 1 time; With the engine running 2 times.
The display will show the error code stored in the "d1" field. Codes consist of a letter and a four-digit number. The code in this field will be displayed until the next field is selected with the Mode button or the reading of codes is completed.
Important note: with active codes, the lamp " Mode ON" lights up (Red LED on the mode switching button). Only active codes lead to blocking of automatic transmission functions.
End reading. To leave the diagnostic mode, select the neutral or press the "Menu" button or simultaneously two arrow keys until the display shows "N N "
===================================================================================================
someguy,
I have only had this bus for about 2 months. I am only now starting to read/learn about codes, etc. Therefore, this conversation could go on and on, based on my ignorance, and I don't know how much time you have!
I'm getting from you that there is a way of reading codes, but not with a separate code reading unit of some kind that needs to be plugged in to the system??? (by sequence of pushing buttons on the dash?). I figured that some kind of computer was needed to plug in for reading the codes, similar to a car. Is that not the case?
For the simpler questions, no, I have not cut or worked on any other wiring but the overhead compartments since last running the bus. The wires are still hanging down with the respective pinned couplers on them (I didn't do a wholesale chopping). With that being said, and from what you are saying about the 120 ohm resistor, it appears that there is a way to trick the system.
The overhead bays did have A/C in them. There were several relays up there (the 1" black cube type), and the many white 24 volt light ballasts . I still have all that stuff unplugged but intact (I believe). There was also the wiring to the upper marker lights that will need to be reconnected. It seems like the main issue would be that the system thinks the wheelchair door is open, and then keeping the bus from being drivable.
At this point, without a manual, I'll have to learn how to access/read the codes, and look at the wiring that I still have and see what is involved there. There are only 2 sets of wires (2-3 wires in each) that went from the bays (besides the marker lights) to anywhere besides the bays, and those go through the floor right next to the wheelchair door. All the rest terminated within the bays.
Thanks for all your hard work on this. Your time and expertise is much appreciated! I hope to learn more from you.
The Allision will not display a interlock code ,your network failure on the dash is what you get tell us are the park brake lights on the rear working,if you have the kneel engaged the the D will start and idle and the transmission will not engage,with the high rise on the rear engaged the transmission will engaged they will move at a reduced engine speed,you will find the problem it worked before and will work again with patience,if the rear brake lights are not working the fast idle will not engage.
Ok, so I dug up these (attached pics) control modules (for lack of a better term) and relay/fuse clusters. The 2 plugs that stick out of the modules connect to the gray sheathed wires that are still hanging intact with the respective plugs from the ceiling. I can easily reattach them, but the wires where they led to are a different story. I believe I have the full harnesses, but they only went to stuff within the bays, with the exception of the (2) 2 wire harnesses that go through the floor near the wheelchair door, and the wires that went to the clearance lights.
To see codes on Allison b500 or similar, press both arrows at the same time, twice, then display should flash d 1 x x x x
The x's represent a 4 digit code
If there is nothing after d 1 then the tranny is not throwing any codes
If there is a code write it down, (it will repeat itself)
And press both arrows again, for d 2 etc.
I think it goes to d 4
HTH
Does the pad say "Do Not Shift "
Quote from: 6805eagleguy on October 06, 2020, 03:19:10 PM
To see codes on Allison b500 or similar, press both arrows at the same time, twice, then display should flash d 1 x x x x
The x's represent a 4 digit code
If there is nothing after d 1 then the tranny is not throwing any codes
If there is a code write it down, (it will repeat itself)
And press both arrows again, for d 2 etc.
I think it goes to d 4
HTH
I have reconnected the 2 black boxes and now the "Network Failure" light is gone. However, the WCL Door light is still on, and there is still no fuel pedal, high idle, or shifting. There is no indicator (like luvrbus asked) that says "do not shift", but the D and R light on the shift panel flashes showing that it will not shift (until you press the brake all the way to the floor, then you can shift when the D and R light goes solid, but now that won't work).
I don't know which "arrows" everyone is speaking of when pulling codes. Are they the up and down arrows on the shift pad? If so, where do the codes show up, on the dash? I'll try those arrows and see what I get.
Is there a possibility that with the wiring to the wheelchair door disconnected, that the bus won't shift or no throttle?
Obviously I have a lot to learn, and I will know more than I care to by the time I figure out this problem! I'll be doing whatever it takes to get a manual. MCI isn't very good at getting back to people.
Thanks everyone!
Wheelchair door interlocks are mission critical!
Without continuity, bus is disabled.
The liability and misadventure of driving away with it open or deployed is best left to the imagination. The coach was wired up to prevent the hired gun from trying it...
Restoring the modules is good, now the actual analog bits to the door/lift interlocks need to be fooled into thinking all is closed, stowed, and road ready.
Happy coaching!
Buswarrior
someguy mentioned a 120 ohm resistor bypass. I'm thinking that may already have been done, but that is the part that I cut out when removing the upper bays. There are 3 or 4 of those plug caps/terminations where there is some kind of resistor installed that I took out inadvertently. The wheelchair door or lift hasn't worked in years and it was already unplugged and the door sensors were both either gone and disabled already. My hope is to restore the wires that have those plug cap/terminations in them and hopefully that will restore the bypass that was possibly already accomplished at some time in the past. I'll let everyone know, and that will be the subject of my next "Glennman" video. Thanks!
Glennman, the arrows on the shift pad, then the numbers will read out on top of the shift pad.
I don't think you'll have any codes there, though
The 120 ohm resistor is not to trick anything or replace a sensor. It is to terminate a CANBus network connection. I don't believe your bus has a CANBus on it.
If your network communications error has disappeared then there is nothing that terminating a CANBus will do for you. But maybe your bus has another network that is malfunctioning?
I suspect the wheel chair fault you have is disabling the functions you are trying to make work. (Throttle, transmission, etc.) Is it possible that the terminating resistors you saw were part of the bypassing of the wheelchair system ?
If you ground pins 17 and 19 on the Dimex module that should get you going
Quote from: someguy on October 07, 2020, 11:51:00 AM
The 120 ohm resistor is not to trick anything or replace a sensor. It is to terminate a CANBus network connection. I don't believe your bus has a CANBus on it.
If your network communications error has disappeared then there is nothing that terminating a CANBus will do for you. But maybe your bus has another network that is malfunctioning?
I suspect the wheel chair fault you have is disabling the functions you are trying to make work. (Throttle, transmission, etc.) Is it possible that the terminating resistors you saw were part of the bypassing of the wheelchair system ?
Trick or bypass, that's really what I mean :) I'll be rewiring those terminating resistors back to the system this weekend (hopefully).
Thanks someguy!
Quote from: luvrbus on October 07, 2020, 12:10:21 PM
If you ground pins 17 and 19 on the Dimex module that should get you going
Hey luvrbus, I'm not sure what the Dimex module is, but when I figure that out, do I just attach a wire from those pins to the bus frame? is that what you mean by "ground" the pins?
Yes ground to the frame and look for any broken ground or disconnected ground wires and attach those back