Jump to content

Allision Problems

jd4110

Recommended Posts

jd4110 Enthusiast

jd4110

Posted
Posted

I have a 2001 2500HD 8.1L with the allision, It was working fine last week, drove it home and parked it and did not have any problems. This morning I warmed it up and got in it to go to work and it will not move. I put it in reverse and it is like its in netural, If I put in in D it makes a loud clunk and will move onlly slightly. I don't know if the transmission control mod. can cause this or not, or can a transmission go bad just setting still. Any one had or seen this problem?

Thanks for any help!

 

Just as a note I live in Alabama so it's not real cold and the truck has 89k miles.

By-Tor New Member

By-Tor

Posted
Posted

Same exact thing happened to my 02' HD's Allison last week. I replaced the neutral safety switch and all is fine once again.

 

In addition to what you are experiencing, my gear indicator on the dash was acting up and my doors were not unlocking automatically when I shifted into park.

 

 

It was a 10 minute job and I got the safety switch for $97 from my friend's shop.

 

 

 

Good luck.

By-Tor New Member

By-Tor

Posted
Posted

It's on the drivers side of the tranny. It's located on the gear selector shaft. You'll see where your shift cable goes to the shift arm, the safety switch is about 6" long and the shift shaft slips through it.

 

It might pay for you to take the truck to a shop in your area and see if they can pull the code for you. I can't remember but I think my code was u700 but please don't quote me on that. I do know that the code had to be reset before the truck shifted properly.

Bud Enthusiast

Bud

Posted
Posted
I have a 2001 2500HD 8.1L with the allision, It was working fine last week, drove it home and parked it and did not have any problems.  This morning I warmed it up and got in it to go to work and it will not move. I put it in reverse and it is like its in netural, If I put in in D it makes a loud clunk and will move onlly slightly. I don't know if the transmission control mod. can cause this or not, or can a transmission go bad just setting still. Any one had or seen this problem?

Thanks for any help!

 

Just as a note I live in Alabama so it's not real cold and the truck has 89k miles.

 

 

 

 

Same thing happened to me except mine

sit for about 5 weeks. I had it taken to the

dealer where it worked fine. The story I was told is the

Allison bleeds back trans fluid bad. I was told

that if I had put the truck in park and let it

run for a while it would have been ok. Same

problem as you, I don't know!! Mine has been

fine after that!!

 

Bud :thumbs:

ABQFirefighter Enthusiast

ABQFirefighter

Posted
Posted

jd4110,

My Ally did exactly the same thing. Thought it was the NSBU (neutral safety switch), so I ordered one from GMDieselTech.com. Got the switch overnighted, installed it and all was well, so I thought. I drove it for about 5 miles, parked it, came back out and the tranny was doing it all over again!

I was pretty close to a dealer, so I limped it over there, stuck in 2nd gear. Dealer diagnosed and determined that the TCM (trans computer) was bad. They happened to have one in stock and I needed my truck back. So, $1100 later, the truck was fixed and has been fine ever since. By the way, after I got home, I found the computer at GMPartsDirect.com for around $400 when the dealer got me for $700+. Oh well, had to have it done.

 

Good Luck!

MemphisDoug Enthusiast

MemphisDoug

Posted
Posted

I just had the same problem with my Allison. All kinds of crazy things were happening. The PRNDL was screwed up, I was getting big clunks when shifting between F and R. The truck wouldn't shift past 3rd on the road and I was getting various fault codes. There is a TSB out there about replacing the neutral safety switch with a new one that shields the area where the shaft passes through it. It seems that our trucks throw junk up on the switch when making left turns which eventually shorts it out. The shield is supposed to cure that. The biggest problem I had with changing mine was getting the larger of the two electrical connectors out of it. You would swear it had been super glued into the switch. I had to break the switch away from around the connector to get it out. After replacing the switch and clearing the codes, all was well again.

jd4110 Enthusiast

jd4110

Posted
  • Author
Posted

Thanks to everyone!

I talked to a GM guy yesterday and he said that there was a tech bulletin on the fluid draining down after setting for a while and to put it in Netural for a while then shift gears, so I thought I would try that when I got home, but when I cranked it last night it was already working fine, I drove it to work this morning and so far no problems. We'll see.

Thanks again

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.4k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,837
    Total Members
    8,960
    Most Online
    bellssn690
    Newest Member
    bellssn690
    Joined

  • Who's Online   4 Members, 2 Anonymous, 585 Guests (See full list)

  • Latest Articles

  • Posts

    • Chuck FB
      Gas Prices

      By Chuck FB · Posted

      Interesting, I suspect I would have fueled up in Lee Vining as the day prior I would have filled up either in Laughlin or near there and maybe again before I entered Death Valley and once out the other side late that evening as I kept on driving into the night up near Lee Vining. Next morning I most likely fueled up in LV before heading over Tioga Pass into ( as I refer to it as "Yose .... Mite" 😁 ). And again that was 19 years ago but the price then must not have jumped out at me like the 5 bill a gallon theme of nutty cult hippy country Big Sir or head so far up their rear Aspen. I'd be curious to know where the highest prices are in the lower 48, I probably would not be far off to guess somewhere in Cali forn ie. Coldfoot and Prudhoe bay may have those prices beat but that is a whole other world up there and when prices are more normal elsewhere that is about what they can be up there I believe in no mans land. Anyway interesting that the 395 corridor is hosing people and the thing is, its tourist season and its not like there are a lot of competition options when driving up that highway from what I could see. Yup, big ole Boaterhomes and various other RV's ahead and behind me at the Yosemite entrance gate and they have to get their fuel somewhere.  
    • Atlas
      Gas Prices

      By Atlas · Posted

      Those can be high, as well as the big California cities. The ones that will pop your eyes out are the 395 corridor on the Eastern side of the Sierra Nevadas. Lee Vining, $7.19 for regular and $8.89 for diesel is what the Google said right now.
    • newdude
      2020 Trailboss 6.2 replacement

      By newdude · Posted

      Correct.  2019-2021 model years are serviced by a different p/n.  19420611.  Recall 2021s use 19420611.   The recall engines 2022-2024 model years are serviced with 12740076.     The difference between 19420611 and 12740076 is GM changed injector size for 2022.  The injectors are smaller on 12740076 with smaller injector bores in the cylinder heads to match the smaller injectors.  So you can't install a 19420611 in a 2022-2024, and you can't install a 12740076 in a 2019-2021.     Both engines are the replacement engine p/ns that are in the L87 recall.  So both of these are the updated engines.     Here's a version of the L87 recall with the p/ns for all the parts needed.    RCRIT-25V274-7075.pdf   Note it shows 19420611 and 12740076 with an asterisk to a footnote "Use the VIN and the GM Electronic Parts Catalog (EPC) to determine which part to order if two or more part numbers are listed for the same part, as it may vary by vehicle options."    
    • 2017Z
      2020 Trailboss 6.2 replacement

      By 2017Z · Posted

      Looking for advice from this group. Took my flawless 2020 6.2 TB to an unnamed shop for routine rear brakes and oil change. Tech forgot to put oil back in after the full service and needles to say, destroyed my engine.  It’s all on their shop video so they are responsible.   I had my Chevy dealer do the analysis and they confirmed its compromised and said engine replacement. The manager said they only get GM reman engines from GM with full 3 yr warranty and the one they would put in is not same as what’s they are swapping out on 21-25 for recall.    I am looking for advice why that would be a different engine because obviously I had the good 6.2 year and replacing it has my concerns with that recall for 21-15   Also what’s the pros and cons of accepting the engine swap vs telling the shop that bricked the truck to pay up so I buy a new truck. I’m concerned about stigma resale eventually if I just decide to get rid of it after the swap or other issues showing up after the swap out.  
    • GN2018
      AFM Disabler Question

      By GN2018 · Posted

      Just looked up my records.  I've never gone over 5000 miles between oil changes.  At 46K miles, I have 10 oil changes.  I hope that will help.  I also installed the disabler last year.  I've still had a few times when it didn't seem to engage (which I can tell because the start stop feature kicks in), but for the most part, I think it's working.  For some reason, GM did not include the number of cylinders running in the information screen like I had on other models.  In my Cadillac, it shows me when it's running on 4 cylinders on the fuel milage screen.  I can't find that on my '21 Denali.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...