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Transmission control box

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 85Jimmy, Dec 27, 2001.

  1. 85Jimmy

    85Jimmy Registered Member

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    my 85 jimmy with a 700r4 has an electronic control box under the dash by the fuse box,it says oem replica transmission controller. what does it do and are the switches on the outside of it user adjustable i can't find any info about it from the chilton or haynes books
     
  2. 95 Silverado

    95 Silverado 1/2 ton status

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    sounds like something aftermarket, the torque convertor lock-up would be controlled by the engine ecm, is it still hooked up. if it isn't someone may have used that box to control the torque convertor.

    '95 Chevy Silverado 1500
    5.7 V8-NV4500- 3.73 rears
    See My Toys: <a target="_blank" href=http://community.webshots.com/user/wdb172454>http://community.webshots.com/user/wdb172454</a>
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    The only "transmission controller" you should have in the cab in that area is a light blue or yellow pastic rectangular box, with 3 wires coming out of one side and ?? wires out of the other, which is bolted to the back of your speedometer. (that would be part of your VSS, vehicle speed sensor)

    Probably just a replacement for the stock VSS if it is bolted to the back of the speedo head.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  4. txbartman

    txbartman 1/2 ton status

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    If it is an 85, it doesn't have an ECM. Only electronic control that I am aware of (other than the tranny stuff) on the 85 is the ESC (electronic spark control). Can someone tell me what the hell that is, what it does, and why I need it? (as well as why did they put it in such a difficult to reach place?)

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    ESC I *believe* was ONLY used to retard timing if the knock sensor (part of that system) detected engine knocking. I'm not sure if vehicles still use it, but back then, most cars with ECM's and Chev motors had it as part of the computer harness, so no seperate box like trucks had. Funny, GM "advertised" ESC on the trucks, but not cars lol.

    It's there only to save the motor, not better emissions, as it can retard timing, but mechanical and vacuum advance are still retained. You have a vacuum line going to your distributor? No reason to disable it if it is working fine. If it quit working correctly, I would more than likely disable it.


    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  6. 85Jimmy

    85Jimmy Registered Member

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    the box is about 5in x 5in and has a wiring harness on one side with 18 wires going to it thats all for wiring, it also has a power light and a engage light, plus it has two small adjustable screws one saying system sesitivity and the other says system centering.
     
  7. JIM88K5

    JIM88K5 1/2 ton status

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    I am only familiar w/california emision equiped veh. but it does
    not sound like anything I have ever seen. Sounds aftermarket
    all the way...
    How about a trailer brake control?
    Jim

    88 Silverado K5 5.7-700R-208-10 bolts-4.56-35in
    Procomp AT's- some ORD stuff & a CV driveshaft
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Just looked through my '86 Service Manual, no mention of anything like you are describing. Also agree sounds like a trailer brake, I'm familiar with the ones that are bolted usually to the dash, have a red light that comes on when braking, and have a knob that you can twist to increase or decrease when the trailer brakes apply. I haven't followed up on trailer brakes, perhaps they are all electric now, and don't need that knob, just the screw like you are describing. 18 wires sure sounds like a lot, have you tried tracing a few?

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  9. 85Jimmy

    85Jimmy Registered Member

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    it's also got the normal type trailer brake setup hooked to the bottom of the dash. Its cold up here right now highs around 10 deg and i don't have a garage but i could trace 2 of the wires and they go to the tranny or transfer case
     

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