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TH400 switch pitch question

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  • TH400 switch pitch question

    I have a single wire that goes to a 2 terminal plug/connector on the side of the trans. I assume one's for passing gear. Any easy way to tell which one gets the SP wire? Thanks
    STUGOTS

  • #2
    connect it to one of them and see what happens. If it won't up shift, that's the kickdown. If the converter gets a bit looser, that's the switch pitch.
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    • #3
      The top terminal is horizontal, it's the pressure switch. The vertical terminal below it is the detent or downshift switch.
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      • #4
        I coulda figured that out if I went out and looked at one of my rides.
        My fabulous web page

        "If it don't go, chrome it!" --Stroker McGurk

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        • #5
          Originally posted by Scott Liggett View Post
          The top terminal is horizontal, it's the pressure switch. The vertical terminal below it is the detent or downshift switch.
          Thanks Scott. I have a lot to do on this car and my luck I'd forget about the connection entirely later on when it gets on the road and the trans acts up. My mind would jump to bad trans at that point if enough time lapsed
          STUGOTS

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          • #6
            Originally posted by groucho View Post
            Thanks Scott. I have a lot to do on this car and my luck I'd forget about the connection entirely later on when it gets on the road and the trans acts up. My mind would jump to bad trans at that point if enough time lapsed
            I drove my Caprice for ten years without either connected. Finally hooked up the downshift switch.
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            • #7
              The Caprice probably didn't have a switch pitch converter, it more likely had TCS. The early 70s Chevys usually did. The second wire on those ones is for Transmission Controlled Spark, which changes the vacuum advance depending on what gear the transmission is in.

              Switch Pitch was never installed on a Chevy from the factory....it was a Buick thing, with use on some Cadillacs and Oldsmobiles.
              My fabulous web page

              "If it don't go, chrome it!" --Stroker McGurk

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              • #8
                Originally posted by squirrel View Post
                The Caprice probably didn't have a switch pitch converter, it more likely had TCS. The early 70s Chevys usually did. The second wire on those ones is for Transmission Controlled Spark, which changes the vacuum advance depending on what gear the transmission is in.

                Switch Pitch was never installed on a Chevy from the factory....it was a Buick thing, with use on some Cadillacs and Oldsmobiles.
                I was thinking the same thing. High gear only vacuum advance IIRC was the big thing in that era as an emissions thing (smog device). Which I still don't understand how it helped emissions
                Last edited by groucho; December 18, 2012, 07:55 AM.
                STUGOTS

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