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TACH question, is there a difference in carb/tbi tachs?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jjlaughner, Jan 3, 2003.

  1. jjlaughner

    jjlaughner 3/4 ton status

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    Seems like I remember seeing something about not wiring your tach into the normal places on a TBI because it could short things out?
    Is there a wire in the factory wiring harness you can tap into behind the dash for factory tachs or is it a completely different harness for vehicles with factory tachs?
    Anyone have a wiring diagram for any of the above?
    Thanks, Jeremiah
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    There is a wire off the coil that is for tach signal, IIRC it is a white wire, this is for TBI trucks. If you have an earlier truck with the large HEI dist, then there is a place in the dist cap for tach signal wire.
     
  3. jjlaughner

    jjlaughner 3/4 ton status

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    I'll have to check, my truck I know has the remote HEI coil. I dont remember seeing a spot on the cap during the last tune up. There are a couple connectors on my firewall that have never had anything connected to them and one or two small wires with caps around the injection harness that I have always wondered what they where for. Maybe I'll get some closeup pics this weekend.
    Thanks
    J
     
  4. Thunder

    Thunder 3/4 ton status

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    Use the white wire that comes off the 4 wire connector on the coil. That is the only place to hook it up.
    That is the factory hookup.
    Its the wire I wired my aftermarket tach to it works fine.
     
  5. Sidepipes

    Sidepipes 1/2 ton status

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    I did the same as thunder hooked it into the white "test" hookup off of the coil. Its worked flawlessly for the month I've had it in there.

    I still lhave to find a permanent place for the tach. I currently have it tie straped to the steering column. I don't want to put it on the dash until the Jimmy looks a little meaner( tires bigger than 235/75r15's) Where does everyboy else have them?
     

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