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  1. #1

    Default Speedometer not working, ABS & emergency brake light on!

    Hey folks,

    I have just acquired a 2001 1500HD 4x4 (traded my caddy and $500 for it) and the speedo doesn't work. I changed one speed sensor in the transfer case (even swapped them around...for there is two). I took the cluster out of my 2001 2500HD service truck and all other gauges worked except the speedo.

    The truck just recently had the transmission swapped with a working used one from LKQ. I have been looking for disconnected grounds and sensor pig tails to no avail.

    I get the CO236 code on my ABS DTC but that's all the info I can get.

    I am new to the cite and attempted to do a key word search but got nothing useful.

    Please help,

    2001 1500HD 6.0 4x4 AT
    2001 2500HD 6.0 Service truck

  2. #2


    Found it. It was a plug in the wrong sensor. The main connection is just a two plug like the rest of the magnetic sensors on the transfer case. I paid 40 bucks on ($29+11 tip...VERY PLEASED) to have a master mechanic talk me through it. CHeck out the conversation here|833

    I'm for real. Check it out when you get stumped. If it wasn't for his final color code help, I would have wasted all day and still may not have found it before I spent money on a ABS module, or PCM, ignition switch, etc.


  3. #3
    Sr. Engineer
    Join Date
    Dec 2011
    11-22-boogie woogie avenue


    Most times on these chevy trucks if you have a problem will be a bad connection in harness or ignition switch.

  4. #4


    Quote Originally Posted by dipstick View Post
    Most times on these chevy trucks if you have a problem will be a bad connection in harness or ignition switch.
    Thanks dipstick,

    I will keep an eye out. Getting a crash course on the 6.0 l4q right now. Bought a 2001 2500HD with a bad 6.0 (shredded #1 main bearing) and will pay careful attention to plugs and harnesses in the r&r.


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