Just bought some LED lights for my rig (91 3vze 4runner) and before I fabricate something I'd like to see has someone else found a tried and true way to route a thin wire harness from the engine bay into the cab?

Thanks in advance

 

If you look along the firewall you'll find several rubber grommets where wires and cables already pass through the firewall. You can usually thread a few more along side the existing ones using a stiff wire as a needle and then taping the harness to that to pull it through.

Whatever you do, make sure the hole remains sealed after running the wires. Lots of unpleasant fumes under the hood that you don't want in the cabin. A little RTV will do the trick if necessary.

 

Thanks man. I rummaged around and found one that goes behind the glove box. But the RTV tip is well received.

 

Can't say I'm a big fan of silicone in this application as it's a PITA to deal with after curing.

Aircraft mechanics use Flamemaster CS 1900 to seal firewall penetrations. I'm sure there are other similar materials available at local auto stores.

 

There should also be one behind/above the drivers side kick panel.
For safety, and so you can use thinner wire to cabin:
1) Put relay physically between battery/fuse and lights, but closer to fuse.
2) Tap positive of relay control coil to marker light positive (you get reminder when lights are left on),
3) Run negative side of relay coil to switch in cabin. This wire will carry very little current so can be thin. IF rail lights are on and this wire shorts to ground somewhere, no harm done; your LED light will just turn on.