Brown tachometer wire.

Discussion in 'Electrical Systems' started by z 28 hybrid, Nov 18, 2014.

  1. z 28 hybrid

    z 28 hybrid New Member

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    I have a brown wire that passes through the firewall in its own grommet. It goes to the instrument cluster. I think its for the tach. It won't reach the distributor on the engine side. Am I missing a transducer or something, or should I run the wire straight from the distributor to the cluster?
     
  2. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    I am converting my original dash from non-instrument to U14 and have been going through the wiring for the tach

    Check the 12wire plug that goes into the printed circuit on the back of the instrument cluster. If the brown wire is in connection #1, then it is for the tach.

    There is a light brown wire in connection 4 and a light brown with white stripe in #7.

    I have an HEI distributor and a Mallory tech told me it should work fine without any other components between the distributor and connection #1
     
  3. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    I am assuming your gauge is a Camaro unit mounted in the dash and you also have the Camaro temp and oil pressure gauges
     
  4. orkin

    orkin Veteran Member

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    the tach wire should go through the main harness, that sounds like the blower motor for the heater.
     
  5. 8pack

    8pack Veteran Member Lifetime Gold Member

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    In my 78 it is a separate wire. Brown with its own spot on the firewall.
     
  6. Gary S

    Gary S Administrator Lifetime Gold Member

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    What year is your car? Later cars with HEI had a tach filter mounted on the firewall on the outside. The tach wire went there first, and then from the filter to the distributor. You can usually get by without that filter. Try extending the wire to reach the distributor. If the tach works and gives steady readings, you don't need the filter. It the tach readings fluctuate, you can add a filter to steady the readings.
     
  7. z 28 hybrid

    z 28 hybrid New Member

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    Thanks for the responses. It is a 79 z28. 350, tach in the cluster. The brown wire won't reach the distributor on the firewall side. I am missing something , and the filter sure sounds like what I'm missing. Does it look like a capacitor? Where can I get one? Thanks!
     
  8. greaser

    greaser Veteran Member

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    I have a 80z with U14 gauges. The brown wire is the tach wire, it goes through the firewall then connects to the wire harness. I do not know for light cluster if the brown wire goes to harness or directly to cluster, but according to my 80 wire diagram it would go into harness either way. My brown wire is short also and would not be long enough to go from tach to HEI. Look for a connection point close to where the brown wire comes into the cabin. In mine, a single white wire coming out of harness. And I would expect it feed the filter first also.
     
  9. RS1979

    RS1979 Veteran Member Lifetime Gold Member

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    On my 79, the brown wire is the tach wire also. There should be a plug that will fit the negative connection on the cap. If the wire's not long enough, you can splice some more wire into it to reach your distributor.
     
  10. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

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    If I'm not mistaken on my 79 Berlinetta, the brown tach wire goes thru it's own firewall hole, and into a connector. The connector then goes to the distrib.
     

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