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The Ultimate Tacho Thread

Discussion in 'Electrical Wiring / Questions' started by 253@7k, Jul 28, 2006.

  1. 253@7k

    253@7k 300rwhp supra. yay.

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    Ok I have decided to do my own little bit of cleaning, so please take notice before asking "how do I install a tacho?"

    In this thread you will find links to all kinds of info on tachos. Threads have covered:

    How to install tachos,
    Troubleshooting with tachos and
    Why the hell do you need a tacho in the first place?

    These threads should supply you with all the info you need. (And stop the need for more tacho threads)

    Here we go.....

    Finding the "brown wire"

    Wiring tachos (vn onwards)

    Why do you need a tacho arguement


    More wiring solutions (VY)


    Solving problems with your tacho signal

    And these are just some of the ten thousand million that exist.

    So, to conclude:

    VB-VL= signal wire to coil.

    VN-VX= Signal wire is brown wire near strut tower.

    VY V6= Signal wire is solid brown wire in the loom infront of the coil pack.

    VN's have signal problems. (Some dont send correct signal. Fix with tach adapter)

    These should answer just about any questions you may have. If you need to see what I have said repeated 1000 times just do a search on "tacho".

    Just rember, your commodore probably already has a damn tacho.

    Steve.
     
  2. azzfox

    azzfox Braaap.

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    thankyou, hopfully we wont get anymore tacho threads with questions asked a million times :p
     
  3. Goon

    Goon Scientific Tuning

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    My VC's Speco tacho

    Green to coil
    Red to 12v accessory
    Black to Negative
    White for light, but thats not connected.
     
  4. Pub247

    Pub247 Well-Known Member

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    What's involved in recalibrating a tacho eg vh sle v8 tocho down to a 202 would recalibration be needed?
     
  5. azzfox

    azzfox Braaap.

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    yes, it will need to be changed to suit the 6cyl. if its a stock tacho im not sure if it can be done. if its aftermarket there should be a switch at the back of the tacho.
     
  6. Pub247

    Pub247 Well-Known Member

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    Goon mine is an actual in dash original tacho like instead of where the vac gauge would be. Slundy can you help me will it need doing or should it be right?
     
  7. 253@7k

    253@7k 300rwhp supra. yay.

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    Hmm, for some reason my post did not come up. I'll post it again.

    From what I can tell, changing a v8 tacho to a 6 tacho just requires a resistor in the tacho to be changed. That is as far as I have gotten, I cannot seem to find the exact resistance that is needed. I think we need an elec expert.
     
  8. Pub247

    Pub247 Well-Known Member

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    ok thats cool i havent really looked at it yet and not going to do it yet so i'll pull it apart and have a look
     
  9. Tasmaniak

    Tasmaniak Not a valid input....

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    Stickied

    Recalibrating a tacho cannot be done via a resistor. Putting in a resistor will stop the tacho altogether. Tachos work on pulses of 12 Volts. So, by putting in a resistor it still pulses just at a lower voltage causing the tacho to stop working at all.

    Check on the back of your dashboard circuitry. You MAY find a little switch ;)
     
  10. 253@7k

    253@7k 300rwhp supra. yay.

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    Glad your here to keep us on the strait and narrow, cheers.

    Steve.
     
  11. bangers

    bangers New Member

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    incorrect. the signal wire on a VL does NOT go to the coil! there is a wire behind the instrument cluster. the coil is a multi spark system i believe and will give an incorrect reading. in the Gregory's manual it says there is a signal wire hanging behind the alternator but that is incorrect too, it is only a test wire.
     
  12. 253@7k

    253@7k 300rwhp supra. yay.

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    Ah yes bangers, my mistake I forgot about the rb30's. However V8's should still be able to go to the coil though right?
     
  13. bangers

    bangers New Member

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    i imagine so as the V8 didn't have an ECU. but then like the RB30 the wiring loom may be the same for auto and manual. i can't say for certain.
     
  14. Tasmaniak

    Tasmaniak Not a valid input....

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    Either way....the wire will always be behind the dash as well....
     
  15. Frandy

    Frandy _____________

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    what about installing a stand-alone shift light?? How do you wire one of those up?
     
  16. anton1o

    anton1o [GMHVN6]

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    Or installing a water temp gauge, oil temp, oil pressure..
     
  17. 253@7k

    253@7k 300rwhp supra. yay.

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    Read the instructions, there will be a signial wire that will be connected to the same signal wire as your tacho. (see above posts for instructoins on finding wire.)


    A few questions there. Depends on the car, engine and gauge. more info needed.
     
  18. bobhasnoshoes

    bobhasnoshoes New Member

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    help me

    can some1 plzzzzz help me?!?!, i got a VH Commodore n im lookin to wire up my tacho but i wouldnt have the faintest idea when it come to wiring n electricals. can some one tell me how to do this in a way that even id be able to understand?? cheers
     
  19. Goon

    Goon Scientific Tuning

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    Look at my post above, red will always be postive and black neg, ones lights and the other coil.
     
  20. onedollarshort

    onedollarshort New Member

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    cheers man im havin big dramas with the tacho i got now i own a vt and im trying to put my speco 4 in 1 tacho in and i have got all gauges to work excep the tacho i have tested the tacho on a different car and the tacho itself works fine and i have tested the tacho off the wiring on the guage cluster in my vt and i cant get it to work any suggestions
     

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