Allison 5 speed transmission gremlin?

[codgerbill]

I was on my way home from a trip to South Carolina and coming back to Michigan. I was in cruise control running at 61 MPH or so. The normal operating rpm's were steady at 2100 or there about with a downshift to about 3000 rpm's on inclines and up to 4000 rpm's on steeper inclines. I stopped for gas and after filling up got back on the road. At 61mph the rpm needle was a bit above 2100 and and varying, as I approached an incline the needle would increase up to about 2600 rpm's before finally downshifting to somewhere around 3100-3200 rpms and if the incline got steeper it would downshift to over 4100 rpm's and vary up to 4500 rpms. It was not holding steady at the 2100/3000/4000 rpm's as it was earlier. We stopped for lunch at a rest stop and afterwards got back on the interstate. The rpm's came back to what it was earlier (2100/3000/4000 rpm's). At that point we still had over 600 miles to go to get home and the rpm's never did vary from the 2100/3000/4000 rpm mode again.

I am wondering if this is a precursor to a future problem? As an aside I did have the transmission flushed and filled with new fluid prior to leaving on our trip.

[DriVer]

Quote:

Originally Posted by codgerbill I am wondering if this is a precursor to a future problem? As an aside I did have the transmission flushed and filled with new fluid prior to leaving on our trip.

codgerbill, Not so much of a Gremlin (trouble) as an anomaly. I expect that an electronic event caused the abnormal shift pattern and RPM differential. Since the parameters reset on restart this is where I would place my assumptions.

Keep a weather eye out for it and let us know if the event occurs again. Arrrgh!

[pkmesser]

Sounds like it wasn't achieving torque convertor lockup.

[ronmc]

I don't run in cruise control on inclines or hills.My manual states to use cruise control on level only. Much easier to control RPM's manually.

[TAMU62]

While traveling through Oklahoma and Arkansas I had the Transmission Fail Warning Light come on. After a very start/stop cycles the light when out. Later after a fuel stop the transmission would not get out of third gear no matter what I did. The temp got to about 200 before first place I could stop. Fluid was OK and after a few minutes tried driving again and everything was normal. I went to United Engines at Van Buren, AR to have it checked. They cleared "Locked in Third Gear" code but found no problems. BTW United Engines seems like an excellent shop if you have an Allison problem and it is located very close to I-40 and I-540.

[DriVer]

Quote:

Originally Posted by ronmc I don't run in cruise control on inclines or hills.My manual states to use cruise control on level only. Much easier to control RPM's manually.

In my expereince, manually throttling hills returns better MPGs.

[codgerbill]

TAMU62,

I dunno if this applies in your case, but......
What the cause of my transmission wierd shifting problem (which only happened on a few ocassions, along with a ABS light and a fuel guage that would only read after we traveled about 7 miles was...............
A loose connection block. The coach was taken to a workhorse service center a couple times and all they did was replace an ABS sensor and recommend we replace the fuel pump and the fuel level indicator in the fuel tank. They were not able to diagnose the shifting problem either.
A local auto shop (they service my RV) actually slid under the coach to inspect the sensor and the connections and found the loose connection block.

[wa8yxm]

I think things get flatter as you get closer to MI.. By the way.. I just went the other way and am currently in GA.

Try south bound US-23 approaching I-96 and see what happens.

[Max Hubrich]

I finally found the "perfect road" for my cruise control.

It is the "New Jersey Turnpike". My little bit of research on the internet shows that the NJT was designed to be FLAT. All intersecting roads were raised over the Turnpike-. I can actually sit back and enjoy the cruise control for once in my ownership of this WH/GM engineered CC. No inclines, hills or slopes. I've just given up on using it anyplace else in the world.

Now if they would/could have engineered in less traffic-

[DriVer]

Quote:

Originally Posted by Max Hubrich Now if they would/could have engineered in less traffic-

Hey Max, Going south on I-95 is all downhill! Piece of cake.

[trophylite]

I have a question regarding a 2005 5 speed allison.. When downshifting automatically into 1st gear, about half the time I get a clunking noise like it's going into first gear hard.. Is this normal, or does it sound like I have a problem.. MH only has about 16,000 miles on it...Any ideas

[mfire1339]

Not normal.



Mike

[xctraveler]

OP, in reading your post I see the problem began after a fuel stop presumably with the engine hot from running. I have had a couple of instances of transmission going into limp home mode after an abbreviated fuel stop (that is no wait in line for a pump and no waiting to pay) in hot weather particularly when climbing hills.

Everything is hot and quick access to the pump means no idling and and then stopped long enough for heat soak to raise temps in tranny and engine. Tranny oil may froth and require some cool down (idle in place for 10 minutes) and a restart to reset the fault. The explanation is from a Workhorse engineer, I have confirmed it with Allison. This may or may not be your problem.

[CoastieSCPO]

xctaveler gives very good advise. What he describes has happened to me. Insofar as running up and down hills in cruise control, I never do it. Only on flat land. You will put much less stress on both the engine and transmission by controlling your speed and gear when not in cruise, IMHO. Not only that, put you will get better gas mileage as DriVer said.