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Resistor on the Firewall - 81 Z28 - What does it go to?

Discussion in 'Troubleshooting & Diagnosis' started by FooFighter, Feb 21, 2021.

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  1. Feb 21, 2021 #1
    FooFighter

    FooFighter Member Gold Member

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    This resistor /ballast, not sure what it is, was on my firewall and I don't know if it was connected to anything or not, it might have been connected to the tach lead, but I took it apart so long ago I don't remember.
    Anybody know what it goes to or its purpose?

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    Last edited: Feb 22, 2021
  2. Feb 21, 2021 #2
    tom3

    tom3 Veteran Member

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    Looks like a noise suppressor, a capacitor. For a CB radio back in the day maybe?
     
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  3. Feb 21, 2021 #3
    BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    Tach lead
     
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  4. Feb 21, 2021 #4
    FooFighter

    FooFighter Member Gold Member

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    Does the Tach Lead connect to that ballast/resistor pictured above? As I have a picture of the Tach Lead posted below:
    The Tach Lead went straight through the firewall and connected to a white wire inside the cabin. Has a grommet in the middle of it where it goes through firewall.

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    Last edited: Feb 22, 2021
  5. Feb 21, 2021 #5
    Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    I remember there being a Transmission Controlled Spark module on the firewall of my '71 that looked kinda like that. It failed, and we bridged it.
     
  6. Feb 22, 2021 #6
    FooFighter

    FooFighter Member Gold Member

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    After some digging around here's what I think it is, I think it is the Tach Filter (one end connects to distributor and the other end connects to Tach Lead Extension wire), the Tach Lead Extension wire then passes through the firewall and connects to a white wire that runs to the circuit board of the cluster and finally to the Tach. Does that sound right? What makes it hard to tell is that the Tach Filter connector is broken (the part that I think connects to the Tach Lead extension) so I can't actually connect the two wires to see if they were a match fit. I do have pictures of before I took the car apart and the Tach Filter wire was electrical taped to what appears to be the Tach Lead Extension. Can't tell for sure as the Tach Lead Extension runs behind the brake booster and the picture didn't show behind the brake booster.
     
  7. Feb 22, 2021 #7
    DougD

    DougD Member

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    It is indeed a tach filter. You can get some generic replacements. If you want that actual style, you won't find it easily. Look at Eckler's for a Corvette one, you'll match it right up
     
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  8. Feb 22, 2021 #8
    carhead22000

    carhead22000 oldblue

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    noise suppresser for radio
     
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  9. Feb 22, 2021 #9
    FooFighter

    FooFighter Member Gold Member

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    Thanks for the help guys!
     
  10. Feb 23, 2021 #10
    tom3

    tom3 Veteran Member

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