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Thread: 4x4 wire harness question. How does this work?!

  1. #1
    Join Date
    Apr 2007
    Location
    Utah
    Posts
    71
    I have had a wire harness made for my 2004 K2500 HD Transfercase so that I could plug it into my truck along with the 6.0 and 4l80e. I have wire diagrams for a 2004 cheverolet chevy K silverado 4wd. The problem is that the wire harness was originally built for a the 1/2 ton shift control module rather than the heavy duty one. I am told that the only difference between the two in the speed sensors on the T case.

    Is this True?

    Also, the bigger problem is that I am not getting the shift control module to "power up" so nothing seems to work. I have ground and 12 volt reference but for the loop that activates the shift control module I have no power, or five volt reference. The only wire that I can see that is out of place is one purple and white wire that lights up the control switch, according to my diagram it should is in the right place but when I manually test it the wire should be moved over one place. Does anyone know where or how the control module gets power so I can get this thing to work?

    I do not have the schematics for data link communications, is there any chance this is what turns the loop on? There is one wire that goes to the PCM and as near as I can tell it is in the right place.

    Sorry for all the details, but I am praying someone knows how to help me!

    Thanks
    1990 K2500 with Hummer Kit Body, LQ4, 4l80e 4x4

  2. #2
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    Contact whomever made the harness and ask them how to make it work. Surely they knew what they were doing when they wired it up.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  3. #3
    Join Date
    Apr 2007
    Location
    Utah
    Posts
    71
    <div class='quotetop'>QUOTE(RedHeartbeat &#064; Jun 29 2007, 12&#58;04 PM) [snapback]98123[/snapback]</div>
    Contact whomever made the harness and ask them how to make it work. Surely they knew what they were doing when they wired it up.
    [/b]
    I have at least once and didn&#39;t get any clear anwser. I know know after a few more checks with actual trucks with this set up and there is at least one wire missing. The buy who made the harness thinks that the 4x4 harness is the same between the 1/2 tons and the HDs and that there is a different shift control module and a few speed sensors between the two. My fear is that he is wrong and I&#39;ll need to pull the whole harness out and have him remake it.
    1990 K2500 with Hummer Kit Body, LQ4, 4l80e 4x4

  4. #4
    Join Date
    Apr 2007
    Location
    Utah
    Posts
    71
    <div class='quotetop'>QUOTE(kdog &#064; Jun 29 2007, 05&#58;00 PM) [snapback]98146[/snapback]</div>
    I have at least once and didn&#39;t get any clear anwser. I know know after a few more checks with actual trucks with this set up and there is at least one wire missing. The buy who made the harness thinks that the 4x4 harness is the same between the 1/2 tons and the HDs and that there is a different shift control module and a few speed sensors between the two. My fear is that he is wrong and I&#39;ll need to pull the whole harness out and have him remake it.
    [/b]
    It looks like there are two schematics indeed and yes I will have to ship the harness back to him to redo.
    1990 K2500 with Hummer Kit Body, LQ4, 4l80e 4x4

  5. #5
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    Damn the luck. Oh well, hopefully you can afford the down time and have a backup vehicle to drive. Get it done right and you&#39;ll never regret having to wait.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  6. #6
    Join Date
    Apr 2007
    Location
    Utah
    Posts
    71
    <div class='quotetop'>QUOTE(RedHeartbeat &#064; Jul 2 2007, 02&#58;55 PM) [snapback]98384[/snapback]</div>
    Damn the luck. Oh well, hopefully you can afford the down time and have a backup vehicle to drive. Get it done right and you&#39;ll never regret having to wait.
    [/b]
    Fortunately, it is just the 4x4 harness that I have to send back so the truck will still be able to run...Although I currently have it at the Tranny shop to get the TCC code worked out.
    1990 K2500 with Hummer Kit Body, LQ4, 4l80e 4x4

  7. #7
    <div class='quotetop'>QUOTE(kdog &#064; Jun 29 2007, 11&#58;36 AM) [snapback]98119[/snapback]</div>
    I have had a wire harness made for my 2004 K2500 HD Transfercase so that I could plug it into my truck along with the 6.0 and 4l80e. I have wire diagrams for a 2004 cheverolet chevy K silverado 4wd. The problem is that the wire harness was originally built for a the 1/2 ton shift control module rather than the heavy duty one. I am told that the only difference between the two in the speed sensors on the T case.

    Is this True?[/b]
    no, it is not true, the pin out on the transmission plug is different than the 60e tow wires swapped plus an
    ISS is used on the 80e the 60e does not use an Input Shaft Speed (ISS) sensor

    airdeano


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