Trouble Code # PO700 - PO746

Discussion in 'GM Allison' started by stickfolk, Jan 18, 2009.

  1. stickfolk

    stickfolk New Member

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    What does trouble code PO700 & PO746 Mean? Specaly PO746
    I have a 2002 HD2500 with a LB7 duramax and a allison trans with 198??? miles on it. The truck is running about 90 hp over stock with a program.I was merging into traffic getting on to the interstate and threw it to the floor from about40 mph and got up to around 85 mph when I thought it was going to shift into high gear when all of a sudden it dropped a gear like you down shifted it to 3rd I think? and the engine revved up and it felt like you hit the brake. After that the service engine light came on. The trans stayed locked into I think 3rd gear until I had to drive it like that for a little while until I had a chance to shut the truck off. Started the truck a little while later and drove like nothing ever happened and the trans worked fine. I scanned the codes and got PO700 & PO746 with a short explanation then I cleared the codes. I was wondering if the extra HP & TORQUE was to much for the stock allison and maybe that was the reason the trans did what it did. I haven't ran my truck hard sense that and normally don't. Any information would be appreciate.

    Gary
     
  2. BoostN

    BoostN Administrator Staff Member

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    It sounds like you limped your Allison.

    Limp is simply when you over power it such as using a programmer turned up to high.

    The Code P0700 is telling you that their are additional codes stored in the TCM that need to be read. That will really tell you the problem. I would bet you limped it accelerating hard like that.

    Most of the time to fix it from happening again, you would need a Rebuild Kit. Suncoast sells the Kits. I'm actually getting a Stage 4 Kit from them myself to put in my transmission.

    If you don't want to fork out the money I would simply turn the programmer down and not be as hard on the 4-5 shift.
     
  3. stickfolk

    stickfolk New Member

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    Jeff
    Thanks for the reply back, that's what I thought. I got the truck a couple of month ago and I don't know a whole lot about the LB7 duramax and the allison. I installed a K&N Cold air kit, 4" turbo back exhaust and a superchip cortex programer. That is for the most part all I want to do to it. As i stated before the truck has 198??? miles on it and I don't want to kill it so I will be going back to tow/performance mode, all I want to do is wake it up a little. One other question? how many miles will these LB7 & Allisons transmissions last if you treat them good. I have known the truck since new and the truck has been serviced on a maintenance schedule fruo day one.

    Gary
     
  4. BoostN

    BoostN Administrator Staff Member

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    It should be a good truck for you. The only worry will be fuel injectors, have yours been replaced yet? The LB7's are known very well to lose injectors.
     
  5. stickfolk

    stickfolk New Member

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    Jeff
    Yes the injectors were replaced 2 times, once at about 85000 miles then roughly about 25000 miles ago. Will running a programer shorten the life of the injectors do to running more fuel.

    Gary
     
  6. BoostN

    BoostN Administrator Staff Member

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    That's a long debated question. :D

    No one knows..
     
  7. durallymax

    durallymax Moderator

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    The injector failure is a mystery in a sense. we know what goes wrong and how it goes wrong, but it doesnt seem like added power increases the likely hood of failure.

    You definately limped it, ususally they go into 4th gear and wont lock the converter. P0700 is the code you will get whenever the TCM requests an MIL.

    These trucks will last for a long time if kept stock. Your mods are mild so it should last awhile but you may find yourself needing to redo the tranny witht eh added power.
     

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