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  1. #1

    Default 99 Z71 Overdrive/Trans Help

    I recently purchased a 1999 Silverado Z71 Extended cab automatic and about 2 months after i had the truck the overdrive switch stoped working. Now everytime i start the truck the Tow/Haul is Engaged. I can get the Tow/Haul to turn off by puting the truck into drive then back into park. This is the first Chevy truck that i have owned and any help would be greatly appreciated.

  2. #2


    I have a thread on the same switch. Mine doesn't work at all, wont turn on. Chilton manual doesn't address the switch at all, and doesn't show on the wiring schematics unless they call it something other than Tow/Haul like the mfr does, perhaps schematic is labelled with one of those other undefined acronyms like VCS, PCM, ECM, ETC, CPS, MAP, or EBCM.

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