Jump to content

M74 Allison LCT 1000

akduramaxgirl
 Share

Recommended Posts

akduramaxgirl New Member

akduramaxgirl

Posted
Posted

Hey y’all,  I own a 02 duramax 2500hd with the Allison 1000 tranny. I’m having shifting issues or tranny issues, my truck went from going into 3rd gear limp mode to now it throws itself into neutral limp mode when I put it in drive, it’s throwing p0872 DTC, I’m hearing I have a short to ground in either my external or internal wiring harness, I have changed the NSBU ( put the upgrades one on), I replaced the Trim solenoid B, replaced the output speed sensor and replaced the TFPS inside the transmission pan, it’s mounted on the valve body. Has anyone had tranny issues that throw out random DTCs? Sometime it shifts like a dream and other times she’s very temperamental. Thank you 

Mikebtte Enthusiast

Mikebtte

Posted
Posted

As you say sometimes it shifts great and other times it sucks that would tell me it's ether an electrical fault (ground or wiring) or you have something sticking in the valve body. If you have serviced the transmission internal parts I assume you put in new fluids. Did you see any contaminated fluid or old fluid prior to replacement of the internal parts?

How did the wiring look on the inside?

Have not worked on an Allison in a few years. Last stuff I worked on I all required a computer to troubleshoot.

 

akduramaxgirl New Member

akduramaxgirl

Posted
  • Author
Posted

I checked as much as the harness as I could, the wires looked ok, lots a dirt and dust in them. I didn’t look at the wires in the internal harness yet. The fluid smelled a little burned, I checked my fluid level today and it’s over full, so I need to drain some out. I drove it today and it did so good, shifted great had no issues, then came home, shut it off and went to leave like 30 minutes later and back into neutral limp mode it went. Totally different codes this time, p0776, p0700, p0500, I’ve already changed the Trim Solenoid B, I’ll open the pan up tomorrow and check the connections and wires and change the fluid again. 

Mikebtte Enthusiast

Mikebtte

Posted
Posted

Drain the fluid before moving it any more, over full will kill a transmission every time.

  • 7 months later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
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

    342,791
    Total Members
    8,960
    Most Online
    d.lowrey
    Newest Member
    d.lowrey
    Joined

  • Who's Online   0 Members, 0 Anonymous, 4,078 Guests (See full list)

    • There are no registered users currently online

  • Latest Articles

  • Posts

    • Grumpy Bear
      J&L OIL SEPARATOR CO

      By Grumpy Bear · Posted

      Just did an injector/HPFP replacement on Pepper at 192,400 miles; close enough to 200K, RIGHT? (If 200K is considered life end and to me it isn't). But hey, to each his own.    Have never run a catch can on this vehicle. Back side of every valve looked like a new valve spray painted semigloss black. Port walls looked 'neat' (all a normal result of passive EGR via VVT) Zero build up even in AFM cylinders. Just color. It uses no measurable oil and never has.    At 155,000 I put her on E-85 and a borescope of the cylinders at plug change showed very clean pistons and valve faces. The replaced injector tips looked new. (It was the pump piston seal that was leaking). Oh well, have six good backups.    Still gets 28 mpg on gas (highway average) and over 20 (highway) on alky. UOA's look good and runs as good now as it did when I bought it. Better in fact.    What improvement would a Catch Can provide this motor?     And given all this I expect that IF I installed one I'd see some water/gas/oil vapor accumulation. Byproducts of normal combustion.   Having said that, IF my motor used an appreciable amount of oil I'd consider it a useful 'crutch' until I had the situation corrected OR if bore polished, until I junked it or rebuilt it to stave off repeated plug fouling.    I'm not telling you what I THINK. But what its DONE.          
    • Grumpy Bear
      Starting a new thread regarding mounting my 2014 OEM wheels to my 2026

      By Grumpy Bear · Posted

      Love the look. I'm a SCSB lover myself.    Two items. 1.) A spacer changes scrub radius but this also changes when we use wheels of different offsets. A little isn't a big deal. 2.) Steel wheels, alloy wheels all have different thickness. Same effect on the stud and lug nut as a spacer. When hub centric the wheel isn't supported by the stud. It's supported by the hub. The stud just keeps it all together.  
    • JAI3
      2016 Sierra 5.3L L83 new injectors now runs rich.

      By JAI3 · Posted

      I had a evap sol go bad a couple weeks ago. . I replaced it.  While watching live data at the time I saw I had some cylinder 1 misfires. No MIL but on live data I could see ~50 at startup and about 70 more after an hour a drive all on cyl 1.  I also noticed that the LTFT were -5% to -15% always.  And that bank 2 is always -3% richer than bank 1. Even across all driving modes, city, highway, etc it’s always 3% richer than bank 1. So I start with the misfire. Swapped coil, plug, and plug wires from 1 to 3. No follow. I got an Injector reseal kit, pulled the D/s injector rail, swapped #1 and #3 injectors, resealed them, reinstalled and retested.  The misfire followed to 3. So I ordered and replaced all 8 injectors, spark plugs, and plug wires. Also replaced the 1 time use fuel pipes under the intake manifold.  Injectors that were in the truck since new were  Part # 12668390.  I replaced them with # 12742701 Got from RockAuto. Pretty certain they’re genuine and the correct ones. I called a friend at a parts store who told me “the 12742701 were the correct superseded part # for the originals I was replacing”. So started truck after replacing all that and it’s running -15 - -30 LTFTs. I reset the fuel trims with GDS2 and drove it for a 60 miles trip each way. There have been no changes in the LTFTs.  I checked if the HPFP was leaking into the crankcase. I removed the pvc and watched the trims. No difference.  I checked the alcohol content and it was at 10%  I’m out of ideas here. Truck seems to run great. Just always rich on the fuel trims.  Anyone with any help or ideas would be greatly appreciated.  I ran an injector balance test just for the heck of it and it came back this. I’m confused.  I have gds2 and some other diag tools if anyone knows of anything I should test next.
    • Coastie05
      Will not stay in Reverse

      By Coastie05 · Posted

      Definitely needs to go back to the dealer. 
    • Grumpy Bear
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Grumpy Bear · Posted

      No, but don't skimp on safe! 😉 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...