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1993 GMC Sonoma Question: Where do you connect a tachometer to check the Revolutions Per Minute at an idle

 

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scarf, 2.5L 4 Cylinder, Scottsdale, AZ, February 21, 2014, 17:24
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I have replaced the throttle body and need to verify engine speed

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    G. T. Service Center (4142 Answers) , Stephenville, TX - (254) 638-3236
    ProfessorG February 21, 2014, 17:45
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    Negative side of the coil.

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    scarf, February 21, 2014, 18:51
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    There are 5 wires running to two separate plugs, which one is negative, and do I pierce the wire?

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    ProfessorG, February 21, 2014, 19:54
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    The white wire with the pnk/blk, the other white wire is a digital signal for the instrument cluster, if the tach is digital use that one.

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    scarf, February 21, 2014, 20:47
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    Thanks a bunch

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    ProfessorG, February 21, 2014, 20:49
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    I was tied up earlier, No Worries.

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  • Medium-star Best Answer
    pushrod February 21, 2014, 21:27
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    Engune idle speed is not adjustablle! That screw is only a throttle stop, ecm has control over idle through IAC valve!!

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