Allison Tranny "does not shift"

[Cragars]

Hello, getting ready for cross country trip but having trouble with my 94 Monaco. Won't start from key switch and no power to transmission shift pad. HELP ME!

[twinboat]

The last three folks who had this problem found the power lead or inline fuse, that supplies the transmissions electronic controller, broken or corroded.

The wire comes directly from the battery and the fuse is buried in the harness.

[MSHappyCampers]

Hi ! Welcome to IRV2! We're sure glad you joined the gang!

Hopefully twinboat has solved your problem!

Good luck, happy trails, and God bless!

[TonyDi]

Glad to have you here in the forum with us. You're gonna like it here.

Happy Trails!!!

[Nasdaqsam]

Originally Posted by Cragars

Hello, getting ready for cross country trip but having trouble with my 94 Monaco. Won't start from key switch and no power to transmission shift pad. HELP ME!

I had a similar issue found the fuse under the side rest where the shift control is was burnt out. They hide the fuses in some pretty crazy places. Good luck

[YC1]

Hello and welcome.

Now rush back to the engine compartment and see if there is a start switch inside that area the is in the wrong position. It seems those that have a starting switch back there run into this issue often.

[stuben]

The TCM requires a continuous power. unplug it and and take it to a bus transmission shop and they can read the fault code. TCM (transmission control module) had a lot of problems for about 6 years in your vintage. Could be power issue or a bad TCM. if it is power, run a new dedicate line from the battery, i had to do that tofu mine. cost too much to chase 3 miles of wire for a short

[Cragars]

Can you replace the TCM with a used TCM with same part number and is the same as the original or is there programming involved so you cannot just swap out? I still have not found any fuses in the wiring harness . Not in back near the engine or under the shift pad. I am really frosted at this point. I appreciate any ideas. I like the idea of a direct power line from the battery but not clear where it goes to on the TCM. I’m guessing I need to clarify which wire and there are many is the existing power lead to the TCM. Can you clarify.

[RamiDav]

When was it working last ?
Does the key turn other things on ?
Have you done any work on the coach recently ?
Many times when we think back we can go back
and find a loose wire or a connector jarred loose .

As was stated above Monaco ran a hot wire directly
to the trans ecm , some time this wire is actually
connected to the chassis battery positive post
but it may be connected somewhere farther down .
This can make it a real mess to find and to make matters
worse some people have found the in line fuse
wrapped up with tape in the harness .
Others have found a butt connector not properly
compress come loose .

Honestly if it were me I would find where power enters
the ecm and try to introduce 12v there , fused of course .
If the shift panel comes alive I would cut the old wire
near the ecm and run a new separate wire .
The new wire should be routed in as safe a manner as
you can with a fuse at or near the batt .

Ray

[YC1]

The tcm on mine is programmed. I suspect an allison dealer can put it on a computer and test it. They were able to pull the programming from mine and hand me a shiny new one for only $1,000

This is not a cheap item so tossing a new one at it might be very expensive and futile.

[Cragars]

Had the TCM tested at a tranny shop and it failed. They then disconnected the shift pad itself and tested that and it was fine. Leaving me with the conclusion I need a new TCM and it is not a power issue. That shop had one but was over 2K and I figured can find it much cheaper and I have for the grand mentioned in one of the post. Maybe it would be wise to like you say introduce power and see if it lights up. Temporary on the floor would be relatively simple I’m guessing. To answer some of your Q’s. Was starting it a couple times a month parked here at my home and quit starting about 6 mos ago.
The key will light up everything at the dash but no power to the TCM and the “do not shift” is lit up. I have hot started the eng in the back but still no power to TCM.
I actually did go back and check closely as had exhaust gaskets replaced and all appeared ok. Also just installed new starter and new battery cables (needed) in trying to resolve this. Thanks for the responses, have been extremely helpful.

[clyon51]

You probably have a rear start switch in the rear engine bay. Make sure it is set to Front. Not sure why you would have no power to the trans up front, unless starting is Not set to Front.

[RamiDav]

" New starter and battery cables "

Look around the batteries and the starter wires the ECM power wire may have
been in one those areas .

Ray

[YC1]

Might be able to find a used one.