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4WD service light and “Limp mode”

Discussion in 'Engine & Drivetrain' started by gsxrkid, Oct 16, 2020 at 6:15 PM.

  1. gsxrkid

    gsxrkid TYF Newbie

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    Hey guys, I’m having an intermittent nagging issue with the drivetrain and I just can’t seem to get to the bottom of it. First, I have a 2007 Tahoe 5.3L with the standard 4L60E trans. Sometimes when I hop in and start it, everything is fine, but half the time the CEL comes on, DIC indicates “Service 4wd” and the transmission will be in “Limp mode.” I have visually checked the drivetrain and changed all the fluids from the front diff to the rear diff. I have taken it to a transmission shop and they just throw parts at it that’s costed me $1500 already. They changed the electronic 4wd actuator (unnecessarily), the ignition switch, and performed the TCC re flash service bulletin upon my request from past research. It was good for about 6-8 months after the service bulletin was completed but now it’s back to the same old issue. Please help! I’m tearing my hair out here. Thanks in advance!
     
  2. BG1988

    BG1988 Full Access Member

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    see if you have any pending codes (not all code readers support it) is it reduced engine power??
     
  3. gsxrkid

    gsxrkid TYF Newbie

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    Not reduced engine power, just R and 3rd gear(s) only. I am going to scan the codes again today.. I’ll update on that shortly. The transmission shop cleared all stored codes before this started happening again though.
     
  4. Geotrash

    Geotrash Full Access Member

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    You need a scanner that can get all of the codes from the TCM, BCM and ECM. A tech2 is a wise investment for any owner of these rigs.


    Sent from my iPad using Tapatalk
     
    Fless likes this.
  5. bnjalal

    bnjalal TYF Newbie

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    Having the same issue, and cant drive the truck for the past few months due to this, kindly update if you found out the reason behind this
    So far replaced the actuator, 4wd switch, TCM.
    Now checking the wiring harness, maybe a mouse was hungry ? and next would be the fuse box
    Also a new battery just incase, but the old one was dead anyway
     

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