Tracing wire through firewall

Discussion in 'Electrical Systems' started by 7.62fmj, Jan 22, 2018.

  1. 7.62fmj

    7.62fmj Veteran Member

    164
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    May 16, 2017
    Jacksonville, Fl
    Noob wiring question.
    My choke wire has no power and I've traced it through the loom to the firewall behind the master cylinder, but I cannot find the wire on the interior side.
    Where do these wires pass through? I have the lower dash dropped but am still having trouble finding it.
    There are also multiple wires that are the same/similar green, how do I know which one is the right one?
     
    Last edited: Jan 22, 2018
  2. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    Apr 6, 2004
    Saint Louis, MO USA
    I'm guessing it's on an older Camaro ?.

    Inside the car find the fuse block and between the backside of the fuse block and the interior side of the bulkhead connector, there is a gap that wires from the engine compartment are at coming into the interior and then wires from the backside of the fuse block are also at.

    Chances are you will have to remove the two 5/16" screws diagonally across from each other holding the fuse block and bulkhead connector to the firewall and then next to those holes where those screws pass through are small clips that allow the fuse block to snap together to the firewall bulkhead connector. Once they are unclipped, the two halves can be moved away from each other.

    If you need pictures I can get some tonight as I have a 70's fuse block at home out of a car.

    Jim
     
  3. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    What year Camaro?
    Late model 2nd gens with an electric choke fed power to the choke through the oil pressure sending unit. (Two connections and three wires connected to the sending unit. One of them goes to the choke.)

    So... The choke doesn't get power unless the motor is running and the pressure is up to whatever the sending unit considers adequate pressure.
     
  4. dave@ztech

    dave@ztech Veteran Member Lifetime Gold Member

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    I thought it connected to the temp sender?
     
  5. Gary S

    Gary S Administrator Lifetime Gold Member

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    Bismarck, North Dakota
  6. 7.62fmj

    7.62fmj Veteran Member

    164
    4
    May 16, 2017
    Jacksonville, Fl
    The engine isn't original and the carb originally had a thermal choke. The harness isn't original, colors don't match and a lot of the electrical components like courtesy lamps and cruise control are stripped out. Lots of dead wires too.
    The car is an 81.
     
  7. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Bloomington, MN
    Other members here have added an electric choke to Camaros which originally didn't have one.
    A common splice for that is the power wire to the wiper motor which is fed through the ignition switch.
    (Turn the key and use a test light.)

    The electric choke only draws an amp or two of power so there is no danger of blowing the wiper fuse.
     
  8. 7.62fmj

    7.62fmj Veteran Member

    164
    4
    May 16, 2017
    Jacksonville, Fl
    I actually did splice the wire there, but I want to remove the old wire. The
     
  9. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

    265
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    Apr 6, 2004
    Saint Louis, MO USA
    I would post some good pictures of the wiring and the spot where the wires come from the engine bay into the interior.

    While you could do as Twisted_Metal stated with tapping into the power wire for the wiper motor, I now have to wonder if that circuit is even fused with what you are working with since you say that the harness isn't original. You could do like Twisted_Metal stated with turning the key to run and then using a test light to find a spot to wire in the electric choke but I would also go further and see if that circuit is on a fuse. If that circuit is not fused, then you could have a lot bigger problem with a possible electrical fire should that wire or the wire you are tapping into shorts to ground.
    Also once you find an existing wire to tap into and it is fused, use the same gauge or thicker to run to the electric choke. Just because an electric choke may only draw an amp or two, do not run a 20 gauge wire from the choke to an example, existing fused 16 gauge wire. Fuses are sized to protect particular gauge wires. A good rule is to never attach a smaller gauge wire to an existing wire.

    I also put together some pictures of an original bulkhead connector/fuse block assembly off of my 74 and this might help you with things.

    https://www.flickr.com/photos/121766713@N04/albums/72157691827765644

    Jim
     
  10. 7.62fmj

    7.62fmj Veteran Member

    164
    4
    May 16, 2017
    Jacksonville, Fl
    I used 16ga wire and I did verify that the wiper was fused. So I'm not worried about that and I'm glad it's finally working properly. But it bothers me knowing I have a dead wire just chilling there.
    I will see if I can get pics tomorrow
     

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