Transmission won't shift out of first gear.

[bigcitybob]

Hello everyone, I'm back! Would prefer not to be posting a problem but unfortunately I am. I used my coach yesterday and it ran just fine. Then I got in it today and pulled out of the parking lot and it would not shift out of first gear. I did noticed the speedometer was not working.

This happen to me one time before, the day after I purchased the coach. I had been traveling and pulled over for lunch and I turned the engine off. When I went to leave, it would not change gears. I pulled over turn the engine off and started it several times over 30 minutes and for some reason it corrected itself and away we went. That was 5000 miles ago and we have never had a problem with it again until today. The coach has 57,000 miles on it.

I might also add that the first time it happen we had the transmission looked at and there we're no fault codes and no one could give us an answer as to why it happened.

So if anyone can help it would greatly be appreciated. I have had several things go wrong and POG has been a big help in getting them fixed. Thank you guys for your suggestions and expertise.

BB.
2006 Country Coach XL11.

[dale farley]

Bob, I would give Prevost's hot line (PASS) a call. They should be able to shed some light on the problem.

[Gil_J]

Bob,

I too would call PASS and likely follow that up with a call to Allison.

Based on your symptoms it sounds like it could be the transmission's speed sensor or bad connection to the speed sensor. Given this happened once before and then went away, would lead me to check the connectors. I'm not sure if the transmission even stores codes or for that make raises a code for failed transmission speed sensor.

[Joe Camper]

That is one of those issues that has a guy asking. Why in the world would a engine with a computer not throw a code when something that serious is going on? That is wrong on about 10 different levels.

We will all be interested in what caused that.

[bigcitybob]

Thanks for the feed back. Another learning experience. Gil, you were right, it was the speed sensor. FYI, the transmission does store codes on the shifter. If you push the two arrows at the same time, the light on the shifter will start flashing a set of numbers which will explain what is wrong.

Thanks again for everyones help.

BB

[dale farley]

Bob, Good to hear you found the problem. Where is the sensor located? Was it an expensive fix?

[bigcitybob]

I have no idea where it is located. I had a shop here in Dallas diagnose it and they fixed it. I got on the phone with Prevost and they walked me thru the system to see if any codes showed up which it did. They recommended the shop. The charge was $800.

BB

[truxton]

Bob, what shop did this to you?

The speed sensor is located on the upper side of the transmission and you need to get the bus in the air or off the ground some to reach up and change it. Prevost Mira loma did mine and it had a bucking action when up shifting from start. My bill was under 300.00 dollars.

Later
bv

[rcantrell52]

Bob,
Which service center worked on your transmission? Have you taked your Prevost to the Cummins Care off of I-20 in Grand Prairie? Thanks
Reese

[Gil_J]

Bernie,

This reminds me of a throttle position sensor replacement I did while in Vegas. I bought the insanely over priced TPS from the local Detroit shop. I later discovered the part was a fraction of the price from Prevost. I guess the Detroit shop figures they have a captured customer whereas Prevost passes along their volume discount for non Prevost specific parts.

[truxton]

I'd have to look at the bill but 160.00 sticks in my mind for the sensor and about a hour labor and recalibration of the sensor. This sensor is common, it has a few different symptoms. Mine bucked as I know of others and Bob's would not go into gear. When it does go I can tell you it feels expensive, mine bucked so hard I thought the trans would fall out.

Later
bv

[bigcitybob]

The company was Inland Truck. It is the shop Prevost recommended. Would have love to paid a lot less but what can you do? Thttp://www.inlandtruck.com

[rcantrell52]

Bob,
Thanks for the information on the service center that you used.
Reese

[travelite]

Thanks for the info guys, mine has an ever-so-slight shudder when pulling away from a dead stop, most noticeable when under load as in starting up a slight incline. I had Prevost drive it, but apparently I'm the only one who can feel it. Could be the speed sensor.

[Gil_J]

David,

I took my last coach to the local Detroit/Allison shop when I lived in VA. They hooked up their computer and we took it for a drive. They were able to monitor all aspects of the transmission in real time. I would recommend you try the same.

[BenC]

I have noticed that if you have a transmission retarder, and you have the switch on the dash on, even if the modulation lever is set to off, when you apply the brakes, you get 33, 66, and 100% use of the retarder when pressing the brake pedal to 2psi, 4psi, and 6 psi. The shuttering, ever slight, is the rapid change from actively diverting fluid through the retarder and downshift mode, and going back to normal take-off shifting and shutting off the hydraulic fluid flow through the retarder portion. You will know this is what you are feeling if you turn the on/off switch for the retarder to the "off" position and the feel goes away.

Hope this helps.

[travelite]

Excellent Ben! I'll give it a try. It's very possible I'm only feeling this with the retarder dash switch on. I know that I don't feel it all the time and I feel it more when the transmission is cold. I'll play some more and let you know my results. :) When I was at Prevost(TN), Tim connected his laptop to the transmission port and we went for a spin. Everything checked out fine - no codes and no slippage. Here's some screen shots from his laptop.

134431344413445

[travelite]

I have noticed that if you have a transmission retarder, and you have the switch on the dash on, even if the modulation lever is set to off, when you apply the brakes, you get 33, 66, and 100% use of the retarder when pressing the brake pedal to 2psi, 4psi, and 6 psi. The shuttering, ever slight, is the rapid change from actively diverting fluid through the retarder and downshift mode, and going back to normal take-off shifting and shutting off the hydraulic fluid flow through the retarder portion. You will know this is what you are feeling if you turn the on/off switch for the retarder to the "off" position and the feel goes away.

Hope this helps.

Thanks Ben. You were right! I turned off the retarder at the dash switch and the shuttering on takeoff went away. I also noticed that it seems to be peppier off the line. Could the rapid diversion of fluid you spoke of take power away when taking off from a dead stop?