Possible MCI D4500 Computer Problem?

[someguy]

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 ?

[someguy]

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 "
===================================================================================================
 

[Glennman]

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.

[luvrbus]

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.     

[Glennman]

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.

[6805eagleguy]

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

[luvrbus]

Does the pad say "Do Not Shift "

[Glennman]

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!

[buswarrior]

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

[Glennman]

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!

[6805eagleguy]

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

[someguy]

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 ?

[luvrbus]

If you ground pins 17 and 19 on the Dimex module that should get you going

[Glennman]

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!

[Glennman]

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?