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Help! Trans codes galore !

Discussion in 'Engine & Drivetrain' started by Kfnvhi, Dec 1, 2017.

  1. Kfnvhi

    Kfnvhi Member

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    Just purchased my first Tahoe, 2005 Z71. Everything was working perfectly until I installed a flashing blue LED fake security light in the dashboard. I tapped the two wires for the LED into the fuse box on the side of the dashboard. The LED was working fine, but now either coincidentally or as a result of what I did the check engine light is on and the transmission is in limp in. PO codes 758 740 753 785 2761 are coming up. I did check all the fuses I could find and everything seems good. Could this be something I did in the fuse box or is it just something like a bad ignition switch?
     
  2. Locksmith

    Locksmith Member

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    I bought an 03 Envoy SLE for $850 with 186000 on the odometer, and this money pit has cost me in parts, approximately two grand! Welcome to my world! Disconnect the wires, clear the codes and go from there! Whoever mated a car engine with a computer should be shot!
     
  3. Kfnvhi

    Kfnvhi Member

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    Thanks. Already disconnected everything. Cleared codes. Even left battery disconnected overnight. Codes came right back. From everything I read, if it has multiple codes like this it most likely is an electrical glitch not a failure of the transmission. But it certainly could stem from a bad ignition switch from what I read.
     
    Locksmith and Mooseman like this.
  4. Mooseman

    Mooseman Moderator

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    Definitely a wiring or power issue. The main plug and wiring to the tranny would be suspect as well as the internal wiring. Could also be a ground. Ignition switch would usually have other weirdness associated to it but it's a possibility.
     
  5. Kfnvhi

    Kfnvhi Member

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    Thanks! Guess I will continue probing ☹️
     
  6. Kfnvhi

    Kfnvhi Member

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    Problem is fixed!!!! So awesome. Found that the ignition fuse that powers the trans solenoids wasn’t making good contact in the fuse block. What a relief. Thank you Jesus, and of course this forum
     
    Mooseman, Eric04 and xavierny25 like this.
  7. Reprise

    Reprise Silver Supporter

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    https://www.google.com/url?sa=t&source=web&rct=j&url=#&ved=0ahUKEwid8eWLmezXAhWMzIMKHWGtBYgQwqsBCCgwAA&usg=AOvVaw0VTJzWxrN8ZFOD4xbU2nov
    (On edit: If the link doesn't resolve, just paste your sentence with the codes into google - you should find a video by May03LT as one of the first links - that's how I found it.)

    The above link should help a bit; it's for a TB, not a Tahoe, but the concepts are the same. It was created by one of our more knowledgeable members.

    Note that the fuse # referenced (47) may be different on your vehicle, or in a different location. Underhood, #47 is a relay on the TB, the fuse # 47 is in the auxiliary box under the 2nd row seat.

    I believe #47 is called IGN 0 ; it's a 10A
    After watching the video, check the corresponding one in the tahoe.

    Both vehicles of that year share the same transmission (4l60e), so there's a good chance the circuitry mentioned above is similar. Note - I'm *not* pointing toward your trans as the issue. All of the sensors related to your codes are fed by the same circuit, which the video explains, so it's likely to be fuse or wiring related.
     
    Locksmith likes this.
  8. Kfnvhi

    Kfnvhi Member

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    Thanks! You we’re dead on. Just posted that I got it fixed. Found that ign o Fuse not making good connection. I appreciate your in depth response
     
  9. Kelly@PCMofNC

    Kelly@PCMofNC Well-Known Member

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    Glad it was something easy!!
     

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