Running wires for lighting through the firewall.

Does anyone have any tips on how to run a few wiring harnesses through the firewall into the cab?

 

Through the preexisting grommet. Mine was near the steering. Every taco should have one I would think. Or you could drill your own hole and put a grommet in..

There's also a grommet under the cab somewhere, by the seat I think, on some if not all.

 

There should be a rubber grommet you can poke through. I ran mine in a similar area^^ wires came out above the pedals somewhere.

 

if your running premade harnesses, be prepared to cut off connectors and resolder them.

something to consider if you want to control a lot of circuits that require relays outside the cab...

run a cat5 cable. you can control up to 8 relays. i would use a cable that has a thick liner.

 

Consolidate the wiring if possible, and / or loom it all together. Take some time to pre-think the wiring and get it set up correctly in advance of trying to go through the firewall.

Locate the grommet that the factory wiring uses to pass through the firewall. If you are looking into the engine compartment it is on the driver's side, about 12" down, pretty obvious as there will be a thick bundle of wrapped wires there.

If looking from the inside, it will be above where your left toes would be if you were sitting in the driver's seat. You can see it and reach it by contorting your body under the dash.

Take a stout piece of wire - I use wire that holds drop ceilings, or an old two way radio antenna, a metal coathanger would work, too. Straighten out about a 12" section. Take a bastard file and rasp the end to a flat one sided point. Securely electrical tape the harness to this "spear" about 4" or so from the point, and taping from the point down (to keep the tape from peeling up in the next step).

Lube the first 4" of thespear and the "fat" part of the taped wiring, then from the inside of the truck, take the spear and punch it through an outer portion of the grommet, angling it slightly away from the factory wiring, and being careful not to poke / rip the factory wires. Shove it through about 5" or so, then go to the engine side and grasp the exposed tip of the spear and pull it and the harness through the grommet.

Pull the wiring to it's final point and loom it from the firewall grommet to it's end point with plastic split loom.