Allison Service

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Allison Service

December 01, 2014, 07:30:21 pm

Looking for recommendations for Allison transmission service in the Pensacola, Florida area. My Trans has thrown a speed sensor code fault, I have tried cleaning and resetting but I still get an intermittent fault which keeps the trans from shifting out of first gear. It has happened four times in the past two years and always when you least expect it. any help appreciated.
Terry

Re: Allison Service

Reply #1 – December 01, 2014, 07:49:07 pm

Terry,

The two speed sensors (should be throwing different codes to identify which one it is) are VERY easy to replace. One bolt, no fluid loss and a quick connect.

Re: Allison Service

Reply #2 – December 01, 2014, 07:59:51 pm

It could also be the wire from the sensor to the allusion computer. Previous owner of my coach had same problem and I have service bill where shop ran a new wire.

Re: Allison Service

Reply #3 – December 01, 2014, 08:09:10 pm

Quote from: wolfe10 – December 01, 2014, 07:49:07 pm

The two speed sensors (should be throwing different codes to identify which one it is) are VERY easy to replace. One bolt, no fluid loss and a quick connect.

+1

We got our replacement output speed sensor from a Freightliner dealer. Just be sure to take your transmission data plate info - they will need the model and serial number of the transmission to make sure you get the right sensor. If output I know the one for transmission with retarder is different than for one without.

Re: Allison Service

Reply #4 – December 01, 2014, 08:20:15 pm

Terry, that coach did that to us two times, both times after it rained and a year or so apart. Both times it had rained while we were parked but it hadn't been driven in the rain. Both times after the engine ran a few minutes and I got nervous about being able to leave the campground, it started working. I didn't find any bad connection and can't remember now what kind of code it returned. We never found the cause. It never acted up when we were driving in the rain and it only happened those two times.

When you figure it out let us know what it was. Has to be something very simple and I still think a connection somewhere.

Re: Allison Service

Reply #5 – December 01, 2014, 08:30:25 pm

Terry,

If you can't fix it yourself, I would recommend Al-Trans Service in Mobile. 251-304-0906. They are an authorized Allison parts-service-warranty center for Al-Ms-La Gulf Coast area. They work on the fire trucks, big rigs and RVs. While I was there they were servicing a Prevost bus. http://www.facebook.com/pages/AL-Trans-Service-Inc-Allison-Transmission-Dealer/169518986391803?sk=info&tab=page_info

I had a problem this past summer with a code 32(direction signals) on an Allison HT746. Took it to them and they diagnosed it quickly, ordered new parts and serviced it for a very reasonable price. Ken Williamson is a great guy and they really know their stuff. I would give Ken a call and discuss it.

Jerry

Re: Allison Service

Reply #6 – December 02, 2014, 12:33:23 pm

Quote from: wolfe10 – December 01, 2014, 07:49:07 pm

Terry,

The two speed sensors (should be throwing different codes to identify which one it is) are VERY easy to replace. One bolt, no fluid loss and a quick connect.

The codes are:
D1 25 11
D2 23 12

Re: Allison Service

Reply #7 – December 02, 2014, 01:29:35 pm

Quote from: CAPEHORN31 – December 02, 2014, 12:33:23 pm

The codes are:
D1 25 11
D2 23 12

First one is Output speed sensor at 0 in 1st gear

Second one is primary shift selector

Allison Transmission Codes Manual

Re: Allison Service

Reply #8 – December 03, 2014, 09:36:23 am

A participant in North to Alaska 2014 Motorcade had a transmission issue that prevented the coach from going into gear. The error according to the code had been corrected with the recommended part more than once in the history of the coach. After a tow from a remote place on the Alaska Highway, an Allison repair facility found the chafed wire in the wiring harness that had been causing errors for several years.

The codes are an excellent diagnostic guide, but it is prudent to check the wiring.

Re: Allison Service

Reply #9 – December 15, 2014, 09:29:41 pm

I took the FT to a Certified Allison service center to troubleshot the codes. They hooked up the computer and verified the codes but they also found the C2 clutch was slipping intermittent which they said could cause the speed sensor to fault. They suggested a rebuild transmission would fix the problem. The only problem is it a $7,320.15 fix. The transmission seems to shift fine to me and I have never noticed any slipping. What would be the problem if I keep driving it as is?

Re: Allison Service

Reply #10 – December 15, 2014, 11:37:41 pm

Out of curiosity when was the oil and filters last changed and what oil is in it?
johnH

Re: Allison Service

Reply #11 – December 16, 2014, 07:03:33 am

Terry, I took that coach to Allison in Oklahoma City for service not long before we got the U320 bug and traded it in at MOT. They changed the fluid and filter and I told them to double check everything else and they pronounced it healthy.

That receipt should have been in the coach. It's hard for me to believe it has a major problem. The previous owners were a couple in Kansas (can't remember their name) and he was meticulous about service.

Re: Allison Service

Reply #12 – December 16, 2014, 08:25:20 am

Quote from: Johnstons – December 16, 2014, 07:03:33 am

Terry, I took that coach to Allison in Oklahoma City for service not long before we got the U320 bug and traded it in at MOT. They changed the fluid and filter and I told them to double check everything else and they pronounced it healthy.

That receipt should have been in the coach. It's hard for me to believe it has a major problem. The previous owners were a couple in Kansas (can't remember their name) and he was meticulous about service.

Hi Rick,
I am not very confident of the diagnosis I received. I watched the computer while they were testing and it showed only a very very small deviation and only after they very aggressive shifting the gears up and down while holding the brake. The only problem I have ever had is the intermitted one I mentioned in my first post. Thanks for the up-dates on the service you did.
Terry

Re: Allison Service

Reply #13 – December 16, 2014, 08:30:02 am

Quote from: John Haygarth – December 15, 2014, 11:37:41 pm

Out of curiosity when was the oil and filters last changed and what oil is in it?
johnH

John, Complete service at MOT late 2012. I have only driven 10,000. it has non-synthetic fluid. I asked the service manager at Al-Trans about changing to synthetic and he said it would not have any affect. Wish it would as it would save a lot on coach bucks.
Terry

Re: Allison Service

Reply #14 – December 16, 2014, 09:07:11 am

Isn't it an Allison requirement to run synthetic? My understanding is they changed the spec., even on the older transmissions. Lots of folks report better trans performance with the syn...

Re: Allison Service

Reply #15 – December 16, 2014, 09:41:36 am

Chuck,

No, not a requirement, but a strong recommendation. Allison publishes very different recommended service intervals with Dexron vs Synthetics such as Transynd, Mobil Delvac™ Synthetic ATF, etc.

And, particularly with a retarder, which Allison classifies as severe duty, the synthetics are highly recommended.

Re: Allison Service

Reply #16 – December 16, 2014, 10:49:21 am

and with that in mind I would take a gamble (due to other repair and cost) and change out filers and use a good synthetic (of course my application would be Torque Drive by Amsoil).
I know, I know, Allison does not recommend this make but that is a "fix" as far as I am concerned and since I changed over 2 yrs ago I bet I have the smoothest shifting and coolest tranny around.
JohnH

Re: Allison Service

Reply #17 – December 16, 2014, 12:58:20 pm

Terry,

On my 93 U300 I have 83000 miles and I didn't know if the tranny had ever been serviced.

I would change the speed sensor first, clear the codes, and drive it for a while to see if the codes come back. It could be a faulty sensor. Since it was serviced recently that shouldn't be a problem.

When I had a problem with a code 32(direction signals) I had shifting problems on my HT746. I had them drop the pan and remove and clean the valve body. It showed some metal in the pan. When that occurs I believe the standard reply in most shops is to tell you a complete rebuild $$$$ will fix the problem. I opted for servicing and new switches.

With new direction switches, changed fluid (Dextron) and filter, clean metal filter screen in the pan, and check main trans pressure @ operating temp, all was good.

Transmission shifts much smoother now and no codes have occurred since the service. This was back in June and I haven't had any more codes.

Jerry

Re: Allison Service

Reply #18 – December 16, 2014, 04:32:34 pm

Speed sensor and/or wire. Make sure those are NOT the problem before going further.

A fancy box that spits out information is still just a box--it doesn't have a brain. The tech is supposed to be the brain (or doctor) and interpret the data.

Re: Allison Service

Reply #19 – December 17, 2014, 05:34:05 pm

Quote from: CAPEHORN31 – December 15, 2014, 09:29:41 pm

I took the FT to a Certified Allison service center to troubleshot the codes. They hooked up the computer and verified the codes but they also found the C2 clutch was slipping intermittent which they said could cause the speed sensor to fault. They suggested a rebuild transmission would fix the problem. The only problem is it a $7,320.15 fix. The transmission seems to shift fine to me and I have never noticed any slipping. What would be the problem if I keep driving it as is?

Any thoughts on having the transmission serviced with transynd to see if it would help. I have never noticed any slipping in the two years that I have owned the coach so having said that, what is the problem just to keep driving the coach? I just hate to spend 8K for something that could or could not fix the original speed sensor intermittent problem. Thoughts?
Terry

Re: Allison Service

Reply #20 – December 17, 2014, 06:20:00 pm

There have been several comments in this thread from people that actually have fixed the problem you are describing.

It is unlikely (though not impossible) oil is the cause of your problem.

Re: Allison Service

Reply #21 – December 17, 2014, 06:27:59 pm

Whether oil is the cause or not, pretty cheap "insurance" to change speed sensors and fluid with a synthetic/filter.

That is exactly what I would do.

With the caveat that when you drop the filters you find evidence of clutch pieces (which I and most others here doubt) you do not put in the fluid, and go with plan B.

Re: Allison Service

Reply #22 – December 17, 2014, 07:10:21 pm

I think there is a Stewart and Stevenson shop in Panama City, I would check with them, sorry I don't have a number for them.

Re: Allison Service

Reply #23 – December 17, 2014, 07:23:28 pm

Quote from: Bill Willett – December 17, 2014, 07:10:21 pm

I think there is a Stewart and Stevenson shop in Panama City, I would check with them, sorry I don't have a number for them.

Per the website service locator

1128 Chestnut Avenue
Panama City, FL 32401
Tel: (850) 763-7656 -

See more at: Stewart & Stevenson | Locations

Re: Allison Service

Reply #24 – December 17, 2014, 10:26:09 pm

@Terry Just like with a doctor before spending that much money I'd look for a second opinion. I wouldn't mention any previous diagnosis so that you don't prejudice their diagnosis.

Edited: Thought I'd add that I've had very good luck with Stewart & Stevenson in Denver. (YMMV)

see ya
ken

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