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Getting wires through grommet in firewall, any pointers?

airmax617

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First, let me start out by saying that I messed up my build by not getting aux switches. I thought car came prewired just missing the switches, bad mistake. This needs to be standard.

I am trying to make up for my mistake and installing the Mopar Auxiliary Switch kit. I am stuck at getting the wiring harness through the rubber grommet in the firewall.

1. The grommet seems sealed with a bunch wires going through it. Do I need to poke a hole through the rubber or try to get it alongside the existing wiring?
2. How do you get enough leverage to get through there when going from the outside to the inside? A lot of electronics blocking the path in the wheel well.

Thanks for your help!

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sass JT

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So here is how I did mine... you can make a slit via anything sharp(knife, razor blade, safety knife.) in between the wires and the side. then I got a long flat head screwdriver. Near the tip, I took what wire I needed to run and black electrical taped it to said screwdriver. Then I pressed that through the slit out the other side. It is double rubber.

now when I did this I went from the engine bay side into the cabin. That was the easiest to go for me.

this is just a way to get said wires through... your experience may be different... also I recommend if you don’t want to do it yourself, you can check how much a professional will charge.
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WhatExit?

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I did that on my 2014 JKUR but I’m not familiar with ours yet. Did you go to the JL forum and see what they’ve done? There must be 3-4 times as many answers to many of our questions over there.
 
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airmax617

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There’s a video for the install that’s pretty good on a JL.

However the firewall step seems to be a lot easier in the video than actuality.
 

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I have a Rubicon and on the drivers side firewall there is a small rubber (round) plug located below the larger plastic one . If you pop that off you'll see some white foam type insulation. On the inside under the dash is a plastic cover that goes across the inner firewall. If you push in with a pointed object (screwdriver whatever) into the white foam type insulation under that plug and have some one watch under the dash you will see that the whole on the engine side goes all the way through firewall. you need to poke something through that whole and the inner soft plastic liner and you can gain access into cab and run wires from engine to inside.
 

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Pulling wire is always easier than pushing wire.

Use a coat hanger or similar rigid wire, make a tight U at the end. Saddle the wires in the U and pinch it shut, then a tight pass of electrical tape to streamline the whole affair.

Use the other end of the coat hanger to make any holes, a slit of any kind will run in the rubber.

Sorry about the switches, those things are unquestionably the lowest cost/highest value accessory available.
 
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airmax617

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RE: driver’s side hole. Good to know thanks! In this case it won’t work because the auxiliary kit runs to the passenger side because it taps into the controllers in the passenger footwell.

RE: pushing / pulling + Slit. Makes sense to pull vs. push. Sounds like I have no choice other then to make the hole. From the videos and other install instructions, it doesn’t sound like cutting has to be done in the JLs (or its being skipped). I am afraid a hole or slit will compromise the water seal. What are your thoughts?
 
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WhatExit?

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I have a Rubicon and on the drivers side firewall there is a small rubber (round) plug located below the larger plastic one . If you pop that off you'll see some white foam type insulation. On the inside under the dash is a plastic cover that goes across the inner firewall. If you push in with a pointed object (screwdriver whatever) into the white foam type insulation under that plug and have some one watch under the dash you will see that the whole on the engine side goes all the way through firewall. you need to poke something through that whole and the inner soft plastic liner and you can gain access into cab and run wires from engine to inside.
Thanks for posting this - that's how I recall it was on my 2014 JK


Pulling wire is always easier than pushing wire.

Use a coat hanger or similar rigid wire, make a tight U at the end. Saddle the wires in the U and pinch it shut, then a tight pass of electrical tape to streamline the whole affair.

Use the other end of the coat hanger to make any holes, a slit of any kind will run in the rubber.

Sorry about the switches, those things are unquestionably the lowest cost/highest value accessory available.

Thanks for posting this - it's exactly how I ran wires on my JK.
 
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airmax617

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Update: ended up having to make room under the wheel well, took off a black box that is to the passenger side of the grommet (See picture). Once off, made a slit and was able to get the harness through by hand. I damaged my connectors earlier with the hanger method so be careful doing . Now need to find connectors and will post here with an update and model number.

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Eternity

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I'll be honest, I like to do things the right way, but when that way is waaaayyy too difficult, I will find another way. I wanted to go through the passenger side fw, but perhaps it is my diesel config that makes that next to impossible.

So, I went a different route:
1) remove little panel between hood and windshield.
2) tilt window forward a little (I just opened the hood and put a pad spacer so I didn't have to remove wipers
3) remove speaker and glove box.
4) route wire under weatherstripping, down past speaker bay and it pops out right above the globe box.

Sooooo much easier. No, not worried about water penetrating. Can easily route many more wires.

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I ran wires for my front trail cam. There was a lone plug below the harness that is just a plug. Pulled it, made a hole then re-installed and ran the wires through it. Once complete I ran some RTV into the hole to make waerproof from the engine compartment
 

ecidiego

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I ran wires for my front trail cam. There was a lone plug below the harness that is just a plug. Pulled it, made a hole then re-installed and ran the wires through it. Once complete I ran some RTV into the hole to make waerproof from the engine compartment
Did you do the OEM trail cam install? Worth the hassle?
 

HorneyBadger

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Did you do the OEM trail cam install? Worth the hassle?
I installed the Z-Automotive Trail cam. The OEM was still back ordered for months when I did it. Insert pins in the 8.4 screen plug and enabled through the Tazer.
 
 



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