2004 MCI J4500 wont move

[DM56]

Hi all.

Long time lurker here, I’ve got a skoolie, but am looking at getting into a Coach!

I may have found “my rig” at an auction.


It is a 2004 J4500. Detroit diesel / Allison transmission.
Not much info, just says it will run, but ”safety switch won’t let it move “.

I’m thinking it’s just a simple thing???

The Coach is about an hour to hour and a half away.

I can look at it before bidding on it.

Has anybody run into something like this?

Any specific place to start looking?

I’m thinking it’s a passenger safety thing, especially as it starts up and runs.

It’s a seated coach at the moment.

Hopefully that’s all that’s needed to get started on this crazy adventure!

Thanks!
D

[luvrbus]

Some type interlock if equipped with a handicap door that is where I would check first

[Coach_and_Crown_Guy]

See my posts regarding Coaches vs school buses. If you still feel the need to do it you'll find out super quick what I was talking about. I've driven J coaches for years in commercial tour service and I can tell you they are very complicated, proprietary, and expensive to the max to keep in running order. With no previous experience yourself you are inviting a real heartache, tons of $$$, and potential life destroying camel into your tent. F.....s go in where Angels fear to tread. I wouldn't want one for myself, and I Love them, as long as someone else pays to keep them repaired. I'd get a J if I had endless money to take care of it. But heh, what do I know.

[DM56]

We’ll, I’m a wee bit scared now, Thanks Coach_and_Crown_Guy !

I looked at a wiring diagram online, it looks like the Bus won’t go into gear unless the brake pedal is fully depressed, if that switch is gone  bad, it won’t move.

Maybe worth looking into. Maybe not. Gotta think on it now.

[luvrbus]

J's are like all the newer buses they were a little head of others with the Multiplex wiring once you understand it you are good to go LOL I don't understand it for sure.I wouldn't be afraid of the J if the tag steering is not worn out, J's are sure nice looking buses

[Jim Blackwood]

Lots of the reasons why I went with the DL. Too many multiplex horror stories. They do look nice, but while beauty is skin deep, ugly goes all the way to the bone. As granny always said, pretty is as pretty does.

Jim

[luvrbus]

Lots of the reasons why I went with the DL. Too many multiplex horror stories. They do look nice, but while beauty is skin deep, ugly goes all the way to the bone. As granny always said, pretty is as pretty does.

Jim

MCI tech is good at walking you through the multiplex system though ,but one has to have some knowledge on how the system works or it all Greek

[DM56]

I’m hoping to go look at it tomorrow.

Is MCI Tech on YouTube? Or???

Thanks for all assistance so far!

[windtrader]

MCI tech is good at walking you through the multiplex system though ,but one has to have some knowledge on how the system works or it all Greek

I have to agree that as all vehicle diagnostic equipment has advanced, the benefits overcome the underlying complexity. Such is the common saying that auto mechanics is less about mechanics and more about computer tech work.

It seems the advanced systems monitor, log, report, etc. so much more about the bus, far more than just engine management but all systems including lighting, tires, transmission, etc. that what it helps report and offer as fixes is really valuable.

When there are problems within the electronic diagnostic system, that is more compliccated but again due to the electronic communication on the far fewer wires, it can be easier to diagnose and resolve faults in that system. CAN bus and One-Wire are so much cleaner than the spaghetti bundle of wires of old.

[Coach_and_Crown_Guy]

Normal procedure to get moving is to make sure these steps are taken.

1. Transmission button and display shows Neutral.
2. You can use the High Idle to build up air faster, it's the switch with the running Jackalope....
    on the left panel near the ignition switch.
3. Let the air pressure build all the way up till the air governor stops at around 120psi
    This is Critical for step #7 to work. On a completely empty bus air system this could easily
    take 10+ minutes so be patient, that's why using high idle is a good idea. It's a very large
    air system
4. Check to make sure the entry door Kneeling feature is raised up to normal height, Off. 
5. Entry door is closed and the latch/claw engaged and pulls it all the way shut. This is all
    operated by the air system and until it's built up won't work as it should. If the door won't
    close (it's air operated) check under the dash above the throttle pedal by the driver's Rt.
    knee for the little lever with the Red plastic ball on it, this is MCI's door air release valve.
    It's needed so the driver can open and close the door by hand with no air pressure on it.
    Move the lever and the door should start to work with the electric door switch on the panel.
    There are also switches on the exterior near the door so you can open the door under air
    power from the outside, so you can effectively lock the door with air as long as strangers
    don't know how to use the switches to open the door..... 
6. Make sure High idle is OFF. after the air is built all the way up.
7. Push the parking brake button Down and apply a FULL service brake pedal application.
    hold that for a couple seconds then release the brake pedal. No switches involved but
    it is required to release the DD3 style parking brake system in use since forever. Actually
    I'm not sure the J's still use the DD3's since they are prone to age related failures, and
    considered obsolete, and have been superseded, but it's always a good procedure to use
    anyway. Old habits die hard. Push DOWN parking brake button then FULL service brake
    application and release.
7. While still applying a moderate service brake pedal pressure now you can punch the "D"
    on the transmission pad and it should go into gear and try to move, hence the brake pedal
    application. This should be all that's needed, for either the Allison transmissions or the other
    ZIF's with the computerized manual transmission and clutch arrangement.

If, after all this, it still is not trying to either go into gear, or move, then you need to start looking
for other types of interlocks (switches, sensors) like the wheel chair lifts, which are another whole
universe of pain, and any other custom additions to the standard MCI as built vehicle.

This procedure I gave is the standard and all that's normally needed assuming everything is
working as it should. Beyond that it indicates the complex interactions that combine to interfere
with a buses' normal simple operations, and the main reason I'm not real interested in getting
anything any newer than about 2000 vintage. A nice clean "D" for me thank you very much.

[Glennman]

I endured that nightmare but got through it. I was able to bypass the brake interlock, the transmission shift lockout (shift inhibitor) and the throttle inhibit. All will render the bus non-drivable and were associated with the wheelchair system (door, cassette, etc.). Those are the root of the system, and once bypassed, you will not have any more trouble with being locked out. The MCI 1-800 tech number is a free and invaluable resource. Now that I've been through it, I have grown comfortable with the multiplex system. Jike Jim Blackwood said, I believe the '98 is the most ideal if you like traditional wiring systems, but the multiplex can be learned. I would not be afraid of the J4500 in the least, and actually, I think the J model is the most stylish (mine is a 2002 D4500). Bite the bullet and get the bus you want!

[luvrbus]

If I was younger a J would be my choice to convert with the spiral stairs and the large door,and would prefer the series 60 over the Cummins or Cat engine offered in the same time frame of under 2010

[someguy]

J's are like all the newer buses they were a little head of others with the Multiplex wiring once you understand it you are good to go LOL I don't understand it for sure.I wouldn't be afraid of the J if the tag steering is not worn out, J's are sure nice looking buses

J's don't have tag steering.  The Es did but it was complicated and I think it too disappeared.    If you need to make a sharp turn or if you need more traction you can lift the tag on a J.  Or if you get a flat tire on the tag.

[someguy]

I believe the '98 is the most ideal if you like traditional wiring systems, but the multiplex can be learned. I would not be afraid of the J4500 in the least, and actually, I think the J model is the most stylish (mine is a 2002 D4500). Bite the bullet and get the bus you want!

Js didn't get the multiplex system until 2003 or so.  Prior to that they have the gold bricks.

[luvrbus]

Js didn't get the multiplex system until 2003 or so.  Prior to that they have the gold bricks.

I have a friend with the model J  RV chassis that has a factory slide  it has multiplex and the follow along steering MCI had it on display at a rally in Primm Nv and that was before 2003 ,he still owns the bus