Running a power cable through firewall

Specifically 7th Generation Accord, but similar on most other models

  1. RogerH69
    Difficulty Level:

    Tools required -

    • Something sharp and round, (a Philips screwdriver will do) so you make an even round hole in the grommet
    • Cable running poles or an unfolded (fairly stiff) wire coat hanger (i'll describe how to use a cable running pole, but the idea is the same if you're using a wire coat hanger)
    • Strong tape, such as duct tape
    The first thing to do is to find which grommet you want to go through. For my CL9. it was recommended to use the big one that is located above where the front passenger's right foot would be (you can;t actually see it from inside the car in my case, but that's fine).

    Then decide if you're going to go from inside the car to the engine bar, or the other way around. In my case, as I couldn't actually see the grommet inside the car (without taking all the ventilation pipes out), I went from the engine bar.

    So, using a Philips screwdriver, pierce a hole through the grommet you have chosen, being careful not to damage the wiring loom that's going through the grommet. Alternatively, if you have a cable running pole with a sharp end, you can use that too, as shown below

    Being wary not to make the hole in the grommet too big, push the pole through the hole about a foot or two. It's best to have someone inside the car to let you know when the can see the pole coming through

    Once you can see it in the inside of the car, carefully pull a little more through (ensuring you don't pull the whole pole through (trying to find the same hole in the grommet can be very difficult and you'll probably end up damaging the grommet more than you need to). Most cable running poles are able to be extended by connecting another pole, so do that if necessary

    Take the wire you want to run through the grommet and connect it to the pole (or whatever accessories came with the cable running pool - DON'T use hooks as they will catch)
    20181219_175918. 20181219_175924.

    Secure the wire using decent strength tape, making it as smooth as possible, but not too thick

    If you used an accessory like I did, connect this to the pole now. NOTE - it's best to twist the POLE when screwing on the cable connection accessory, because if you turn the accessory (with the wire on it) instead, and the wire gets 'coiled, then this may cause the accessory to unscrew while you're pulling it through the grommet and even if it doesn;t detach, it may catch on the grommet / other bits along the way

    Now go back into the engine bay and carefully pull the pole back through. If you need to twist the pole, then twist it CLOCKWISE, or else you may end up unscrewing any pole extensions / accessories you have connected. Here you can see the end of the pole having just come through

    And then eventually the wire

    Keep pulling the wire through until you have enough length in the engine bay (and make sure you don't pull all the wire through obviously)

    In my case I was running this power cable to go through to the fusebox in the driver's footwell, so I used the pole to feed the inside end of the wire through the dash
    20181219_184122. 20181219_184208. 20181219_184220.

Recent Reviews

  1. Guy at H-Tune
    Guy at H-Tune
    Nice work very helpful for anyone that's not done it before. I've ran my power cable for my sub and amp in the exact same way.
    1. RogerH69
      Author's Response
      Thanks :-)
  2. Nighthawk
    Excellent stuff Rog
  3. DrSam
    Great stuff Roger, Nice One!
    1. RogerH69
      Author's Response
      Thanks :-)
  4. SpeedyGee
    Very useful guide Roger!
    1. RogerH69
      Author's Response
      Thanks :-)