How do I get wire thru firewall

Reply Subscribe

Thread Tools

Search this Thread

Feb 28, 2014 | 10:43 PM

george vee

Thread Starter

Le Mans Master

Joined: Jan 2009

Posts: 6,683

Likes: 1,247

From: NYC

2015 C7 of the Year Finalist

How do I get wire thru firewall

Hi, I am installing parking sensors on front and need to get wire into cabin. Does anyone know how to run wires thru firewall.
Thanks, George

Mar 1, 2014 | 04:51 AM

Supermassive

Melting Slicks

Joined: May 2013

Posts: 2,416

Likes: 805

From: Argyle, Texas

I learned a long time ago that trying to get a wire through the wire loom pass thru's is an exercise in futility. I typically route any accessory wiring through the HVAC pass thrus. the rubber seals are easier to get the wire through and you can easily seal around the wire with silicone sealant or whatever you want to use.

Of course I don't have a C7 yet so there may be an easier routing method that i don't know about yet.

There is also the drill method where you go to an auto parts store pick up a rubber grommet for the wire you want to pass thru and drill a hole in the firewall in an inconspicuous spot and seal it. Not the easiest...and you have to drill so there's that.

Just my two cents.

Last edited by Supermassive; Mar 1, 2014 at 04:55 AM.

Mar 1, 2014 | 04:30 PM

Theta

Tech Contributor

Joined: Jan 2006

Posts: 4,761

Likes: 240

From: Saint Louis MO

St. Jude Donor '14-'15

George, I know I have a schematic here of the front wire harness routing. I'm looking through now to see if I can find where your driver's side grommet is.

I will post here as soon as I find that diagram.

Mar 1, 2014 | 04:37 PM

Theta

Tech Contributor

Joined: Jan 2006

Posts: 4,761

Likes: 240

From: Saint Louis MO

St. Jude Donor '14-'15

This is not the exact schematic I was talking about, but I can't find that one at the moment.

There is a wire harness grommet that is deep up in the driver's footwell in the red zone. The green dot approximates the area.

I'm looking to see where that emerges from on the other side, and if it's easily accessible.

I will be working on my car today, so I'll let you know what I see from the engine compartment.

Mar 1, 2014 | 05:27 PM

slief

Melting Slicks

Joined: May 2007

Posts: 3,269

Likes: 25

From: Simi Valley Ca

Quote:

Originally Posted by Theta

I'm looking to see where that emerges from on the other side, and if it's easily accessible.

I will be working on my car today, so I'll let you know what I see from the engine compartment.

Theta, Like I told George in his other thread, remove the drivers side front wheel and either remove or peel back the fender liner. If you get under the car and look straight up along the edge of the firewall about where the clutch pedal is, you will see a grommet under there. That is where/how we ran the wires for my concealed radar install. It's a bit tough to see but under there and fairly easy to sneak the wires through into the cabin. One thing that might help locate it is to remove the panel under the steering column and look at the firewall from inside the car. You will see the grommet near the clutch pedal. That should help in locating it from the outside. You can actually push the grommet out from inside the car and shine a flash light through it which will help in locating it from under the car. It may help to have an extra set of hands to do this.

Last edited by slief; Mar 1, 2014 at 05:31 PM.

Mar 1, 2014 | 05:37 PM

Theta

Tech Contributor

Joined: Jan 2006

Posts: 4,761

Likes: 240

From: Saint Louis MO

St. Jude Donor '14-'15

Thanks, slief!

I didn't see the other thread, but that's great info about the fender liner. I wasn't optimistic that it was accessible from the engine bay, and now we know.

Mar 1, 2014 | 05:54 PM

slief

Melting Slicks

Joined: May 2007

Posts: 3,269

Likes: 25

From: Simi Valley Ca

Quote:

Originally Posted by Theta

Thanks, slief!

I didn't see the other thread, but that's great info about the fender liner. I wasn't optimistic that it was accessible from the engine bay, and now we know.

I got a PM from George a little bit ago. Evidently he found another way to get the wires into the cabin from the same general area. Apparently near the A-Pillar in his case. Maybe he can explain better.

The grommet I used was fairly easy to access once you knew where to look. I think it was for the clutch peddle or something but it was easy to snake the wires through and easy enough to access. We routed a radar sensor line and two diffuser lines through the same grommet.

Mar 2, 2014 | 03:40 PM

BillB3672

Racer

Joined: Mar 2009

Posts: 361

Likes: 4

From: Chandler AZ

Are you installing a curb detector?

If you are installing a curb detector then I have posted photos with embedded instructions on the forum. Search on the forum under (billb3672 Album) It shows the wire routing into the cabin through the door seals and not through the firewall!

Quote:

Originally Posted by george vee

Hi, I am installing parking sensors on front and need to get wire into cabin. Does anyone know how to run wires thru firewall.
Thanks, George