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vacuum modulator on tranny???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Intense Blue, Mar 6, 2002.

  1. Intense Blue

    Intense Blue Registered Member

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    i have a 87 k5 w/350 motor, 700r4 tranny and all is factory. i am looking for the vacuum modulator on the tranny.my truck is shifting a little slow and was thinking maybe the vacuum line went bad, but i dont seem to see one. also there is sensor on the tranny about in the middle of it on the drivers side. what does this do?????
     
  2. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    I don't know 700's very well at all...
    But i'm pretty sure that only the TH350's and 400's have a vaccum line going to the transmission modulator. 700's won't have that.


    As for the sensor?
    What is is where one wire could hook on to?
    maybe the reverse lights switch?
    lockup torque converter?
    Neutral safety switch? Temp gauge?
     
  3. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    no vacume on a 700r.
    and the wires are for the locking convertor i think. i am almost posative of it.
    Grant
     
  4. Thunder

    Thunder 3/4 ton status

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    No vacume modulator on 700r4s . Shift points are adjusted with the TV (throttle valve) cable. its the cable that goes from the TBI/carb to the trans.
    Do a search on" TV cable adjustment" the are a bunch of posts about it and how to do it.
    The wires that go into the trans on the middle of drivers side are for the electric torque convertor lock up. I think there is also a sensor that tells the computer that the tranny is in OD around there somewhere also.
     
  5. Intense Blue

    Intense Blue Registered Member

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    hey thanks alot guys....
     
  6. Intense Blue

    Intense Blue Registered Member

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    the other thing along with this was that i got a code 24...vehicle speed sensor.....and my speedometer does not work, i unplugged it(mech.cable in the back) and plugged it back in and still does not work. i wonder if the gauge is bad now, is the VSS (vehicle speed sensor) located inside the dash cluster???
     

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