Allison B500 6 Speed Flashing/Blinking D/R Light...

[mqbus767]

Hello Bus Nuts,

After working on the bus today, I decided to start it for the first time in roughly a month. She fired up just fine and built-up air slowly, but sufficiently. I decided to try and shift it into gear just to roll forward and back a bit and ran into the following issue:

1. Release paring break
2. Full service break press and release (parking break light goes off)
3. Press 'D' on the shift pad
4. High idle goes off
5. "6" is displayed and flashes
6. Trans does not go into gear
7. Same thing if I press 'R', 'R' is displayed and flashes.

More pertinent information:
* 2001 MCI 102 DL3
* I forgot the diagnostic code display (press up and down button together once), so I don't know if the trans is throwing a code
* I have been removing various runs of wire related to the parcel racks, metro equipment, signage, and wheel chair lift
* The "WCL interlocks" and "Wheel Chair Door Open" tell tales are illuminated because I've removed the wires that connect the door/lock sensors to the multiplex system

I had a similar thing happen when I first got the bus and learned that the order of operations for closing the doors, releasing the parking break, shifting, etc. were important to successfully getting it in gear. This time, however, I'm unable to get it moving with any combination that I tried including a full shutdown and restart.

Do any other 102DL3 owners with the B500 have a guess for me as to what might be wrong? I will try to get back out to the bus later this week to read the diagnostic codes (if any).

Thanks!

[luvrbus]

You have a interlock open circuit probably from removing the wheel chair lift check there 1st

[mqbus767]

Sounds right to me. I was able to locate the wiring diagram for the bus online (http://3dparts.mcicoach.com/DownloadFile.aspx?ManualId=229) and found the circuits for the WCL open door and related interlocks. On page 7H1-4 of my OM I find the following ladder logic:

Figure 6 shows the states required for the shift inhibit
to be released. Reading the chart from left to right:
a. If the engine switch run input is active (module A1,
LED1 on),
b. And the park brake input is inactive (module A1,
LED 3 off),
c. And the service brakes are applied and the 60 psi
pressure switch input is active (module A1, LED 5
on),
d. And the wheelchair master switch input is inactive
(module A4, LED 19 off),
e. And there is no wheelchair lift flag (wheelchair
interlocks not active),
f. And there is no kneeling flag (kneeling interlocks
inactive),
g. Then the B11 module switches the WTEC shift
inhibit port to ground (module B11, LED 5 on). 

I'll see if I can connect up the harness to that section again and clear the transmission lockout.  Will report back. Thanks luvrbus!

[blue_goose]

If you know which wire went to the interlock all you need to do is ground it. 
Jack

[mqbus767]

Thanks for the input luvrbus and Jack.

Spent the day with the bus with the goal of getting it rolling again. It took a bit of trial and error, but indeed if you short to ground input pins 17 and 19 on the A4 Dinex module, the WCL interlocks and wheelchair open door tell tales extinguish and the shift inhibitor disengages. The LEDs on the Dinex modules make troubleshooting quite a bit easier. I'm also a bit more confident now that I can reuse some of the output pins to control a few things in the coach from the dash. It would be amazing to be able to alter the network programming, but the inquiry that I sent to IO Controls has thus far, and not surprisingly, been unrequited.

Spent the rest of the day running down old/unnecessary cable bundles and removing them. The front J-box on this bus is crammed with Metro hacks. Several bus bars, a voltage converter, several runs of wire that literally go nowhere. t's amazing to see how much wire accumulates after 20 years of upgrades. There are sensors for everything; door opens, PA system used/recorded, brakes applied, parking break applied, etc. If you can imagine it, seems like Metro wanted to track it. I may have underestimated the amount of time it's gonna take to clean all of it up, but I think it's worth the time to get it clean and make space for any new wiring.

Thanks again guys. I appreciate the quick/accurate responses. 

[blue_goose]

Don't know where you are. but if you are in my area I will be glad to get all of that stuff out of the ECM
Jack

[mqbus767]

Hey Jack. Thanks for the offer; I sent you a PM.