Firewall Wire Routing

[Panik]

As the title says, for those of you doing mods, how have you routed any new wiring through your Sierra/GMC's firewall?

 

I apologize if this has been covered somewhere and I have missed it in my searching. I am contemplating doing a number of mods to my Sierra which would require running wires into the cab for switching. I'd love to be able to do this relatively cleanly. Any thoughts about:

 

1) Pre-existing unused firewall ports.

 

2) Pulling wires through the door frame. One mine there seems to be a unused hole covered by a plastic/plug?

 

3) Running up through the floor somewhere?

 

4) Coming in through the back of the cab. While haven't checked I do remember reading somewhere that a guy had run control wires for his flashers through the cab vents at the back of his older model crew cab.

 

Thanks in advance.

[surebuttercringe]

I ran the wires for my driving lights through the existing hole where the steering shaft is. There is a flexible rubber piece around it that you can bend back and place wires through.

[Resqu2]

The Emergency brake cable is another good one to follow for a few small wires, that's how I did my FD emergency light.

[Panik]

Thanks for the responses. Sorry I got a bit busy with the kids over the holiday and hadn't had a chance to reply until now. I know plenty of people have run through the steering wheel boot, I'm just a little hesitant about doing so at the moment.

 

Resqu2 - I like the idea of going alongside the e-brake cable what gauge wire did you use and how many runs do you have going through that area?

 

I am going to give a shot at trying to find the mythical accessory harness grommet the upfitters manual recommends for running snowplow wiring: Electrical Manual pg 75 and 76.

 

I would assume that even though my truck is a crew cab the plug should still be there.

[Jack C.]

Help!  I need to run two #4 wires through the firewall on our 2015 GMC Yukon to run a 1500 watt power inverter mounted under the front seat about 12' of wire.  This will power a ventilator and oxygen concentrator for my wife on trips to the doctors offices, she has ALS.  This has to be a first class installation, we can't have the power go down or a short. I  have a Bussman 90 Amp circuit breaker that needs to be mounted in the engine compartment probably on the upper firewall.  I plan on getting power from the spare lug on the fuse block on top of the battery.  The first two feet of wire probably won't be fused or breaker protected as I didn't see any fuse sin this block?  Is there any way to protect this wire in the block?

 

Any help or guidance anyone can provide will be greatly appreciated.

 

Thanks, Jack