[Archived]

Oh ye, as a side note I am just south of Smithfield, NC before I-40 interchange. If anyone has any recommendations for allison service providers that do road side assistance, I would be happy to hear from you. Have a call into a couple based on the Allison website already but best anyone can do that does roadside work is Monday.

[Archived]

Charles, yes I had
that happen to me.

25-11 code, locked in 1st. These are the
steps I was advised to do and it worked.

Turn off engine, turn off master switch, turn off retarder, turn off
ignition. Use your wrist watch or a stop watch with a second hand.
Wait a full minute, no less as it lets the internal electronics reset.

Turn on key switch, wait a full minute to let
electronics reboot.

Turn on Master Switch, wait a full minute.

Crank engine, wait a full minute.

Selector should be reading N

Foot on brake, with two or three seconds
between actions press D, then press N, then press R, then press N and finally,
press D.

Pedal to the metal. If it does not shift, you can then take a
short cut and simply stop, turn everything off and restart, go through the
N,D,N,P,N,D and try again.

The problem is a wire inside the transmission
and you will need to take it to an Allison shop. It will not do it all the time and mine was
doing it during cold weather on initial start up. The last time, It was cold, I just let it
idle for about 20 minutes to warm the Allison fluid and everything worked.

Good luck getting rolling. After it shifts out of 1st and is working, you can turn the retarder back on.

Fred

[Fred F.]

fred,

could the wire be replaced out in the field, or does it require being in a shop? not really that close to a shop and don’t want to put it behind a tow.

will give those steps a try and see if it works.

Oh also what is the “Master Switch” you speak of?

[Fred F.]

Tried those steps with no luck. Will have to wait till Monday for a service center to open and get them out to where I am to look at it. Really not close enough to drive it in 1st gear to one and would rather exhaust having a field tech come out and look before even thinking about putting it on a hook.

[Kent]

If you are unfortunate enough to require a tow, call John Hawkins (cell 423 413-1888) and ask him who to call in your area. John is VP and GM of Miller’s Large Wrecker Division and knows the people qualified to tow a Prevost as he is also an owner of a H3-45

[Archived]

I had this happen to me on a 95 Liberty XL. I was told to remove the sensor at the transmission output shaft and clean it with brake cleaner. Put it back together and everything worked fine. If you decide to try it, hope it works for you.

Good Luck

GQ

[Dick]

Charles,

That sensor is mounted high on the bell housing at the rear of the engine. I had a picture, but can’t find it.

[Richard]

im thinking this is between the tags and forward of the engine. Not really in a position to get in there where I am (no jacks/stands/blocks). If I get a service tech out here, ill have them swap in a new one rather then cleaning… But if I can’t get a new one a cleaning will hopefully work to get me down the road (like JAX).

[Roscoeapproved]

There are 3 sensors that have a wire harness on the outside of the trans. One is engine speed, turbine speed and tailshaft speed. The connection from them to the wire harness usually just need to be seperated sprayed with your favorite lubricant and reconnected. This cures the issue 95% of the time. If you start moving and the speedo stays at 0 it is most likely the tailshaft sensor, It is at the driveshaft end of the trans and plugs into the wire harness there. IF the speedo works and you get the code it is one of the other 2. Those 3 sensors compare the engine speed, turbine (convertor) speed and output. They also contribute to the shift point determination. If you can get the bus to where you can get under it or find a young mechanic you can explain to them what you need done. One time I found a parking lot with a drop off at the edge of it. Backed the bus up and laid in the side of the hill and got to what I needed.

Good Luck

---

Jeff and Lindsay

91 Marathon XL

[Brett]

Thanks Mikee,

When I talk to the shop on Monday morning, I will pass this information off to them to make sure they bring what could potentially be needed as well as what else they suspect. Dont want them running back and forth burning miles and $$ if they dont need to. I did read some info on the turbine speed sensor as a possible issue here as well as the speed sensor. Havent come across anything in regards to the tail speed sensor so that will help direct the tech on what to have with him when he shows up.

As for the symptoms? Yes, when I move the coach, the MPH stay at zero, at a certain speed (probably around 5 mph) a warning sounds, then the pad display blanks out the “select” side and the “monitor” side stays at “1”. Once this happens, you need to bring the coach to a stop, and turn it off (can’t switch between D, N or R).

Just to make sure, I did check the fluid level and it’s showing “ok”.

Guess I’ll get some more time to go visit some historical sites before they are closed down due to hurting some snowflakes feelings.

Thanks

[Fred F.]

Here are pics of the electrical connections at the 3 sensors. In the first pic, 2 of them are at my thumb and index finger and they are on the driver side. The 2nd pic is the one near the driveshaft.

[Archived]

Based on the speedo staying at 0 when you drive, it is most likely the output shaft sensor, or tailshaft sensor. Remove the plug, spray it and reconnect. If this cures it you are good to go. Most of the time the conenction just needs to be refreshed. If that does not do it the tailshaft sensor will need to be replaced. That plug seems to collect dirt and needs to be refreshed more than the other 2.

Let us know the outcome.

Good luck

[Archived]

Forgot to answer your question.

Is it possible to bypass and manually shift.. Short answer is NO

[Archived]

Wow, talk about a nightmare!

I have called literally 2 dozen Allison Certified service centers, mobile/emergency mechanics, etc.. within 50 or so miles.

The allison dealers couldn’t even get me part numbers/availability without the transmission serial #. Of course not being able to get under the coach makes getting the serial number a little difficult. Was just about to call prevost with my VIN when Jeff called me giving me exactly what I needed (I am assuming he called Prevost with my VIN# and got me the Transmission Serail #).

Of course I was still stuck with no one wanting to get under a coach even when I have a paved flat parking lot to work in.

The allison dealer offered to fit me in their schedule if I towed the coach 15 miles up the road. Of course their schedule was 2 weeks out. Really? To swap a sensor (or three sensors)?

So I called Clark Power Services, which is about 100 miles away out on the NC Coast. They had all three sensors and have a tech coming out tomorrow morning. No push back on it being a coach, just a simple “okay, we will bring jack equipment”. I am sure the repair bill will be heavy, but I am not about ready to put this thing on a hook to get some sensors swapped out. Sure it may not be the problem, could be a solenoid, internal something or other. But I would rather try the simple first before having to take a risk with getting it towed. If it works, great, Im on my way and I dont introduce the risk/potential of something going wrong with towing it.

One think I will do now that I have a trailer behind us all the time, is to get a couple 20 ton bottle jacks and some heacy duty stands. Being able to at least get under the coach while on the road is a benefit that makes life that much easier. If I could have gotten under this thing, I would have picked the parts up myself and swapped them in.

[Archived]

Charles,

My speed sensor went south and I changed all 3 because of age but just an FYI.

The speed sensor needs to be calibrated with a reader. I would make sure he brings a laptop with him.

Jeff, is that right?

Later

bv