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'86 Gmc 1500 Computer Controlled Trans?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by pontiacratrod, Jan 12, 2007.

  1. pontiacratrod

    pontiacratrod Registered Member

    Dec 8, 2006
    Likes Received:
    palatine, IL
    Ive Got An '86 Gmc 1500 Suburban W/ A 305 Sb. The Emissions Carb And All That Garbage On Top Is Falling Apart And Not Functioning At All. So I Was Planning On Putting In A Regular Hei And Carb W/out All The Electronics. My Question Is When I Disconnect The Computer Will The Trans Still Work? I Believe It To Be A 700r4 Overdrive Unit.
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
    Likes Received:
    Roy WA
    It *should* work, however you'll either want to check wiring diagrams (dremu has them, so does autozone for most vehicles) and make sure that the lockup is still vaccuum with the CCC setup you've got. I believe it is, but TBI was controlled via the ECM.

    To clarify a bit, you want TCC (torque converter lockup) but it not functioning doesn't mean the trans doesn't shift or anything along those lines. It does however create extra heat and that's very hard on the 700.

    Check the firewall of the truck, engine side. There will probably be two small vacuum switches. The one on the passenger side is the converter switch as I recall. If it's not there, MAYBE the CCC trucks also used the ECM to control converter lockup, but I somewhat doubt that.

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