Finding Firewall Hole in Rav4 to Install Kat's Vehicle Interior Heater

Updated 01/27/2026 | Published 01/05/2026

Question:

I bought a Kat's interior car warmer at Canadian Tire. The cord needs to run under the dash through the firewall to under the hood and out the front of the car to bed plugged into an extension cord into an exterior house outlet. I own a Toyota rav 4. Can someone tell me where to run the cord through the firewall. Any tips and advice greatly appreciated. Toyota will not install it as it is not their product. Canadian tire refused as well despite selling the product. This can't be that difficult.

asked by: Karen P

Expert Reply:

Hey Karen, sorry to hear about the lack of help with the Kat's interior heater part # KH37100! While I don't have the exact hole to use in the firewall of your RAV4 I can point you in the right direction. I would look up under the dash on the driver side and see if you can find any firewall hole grommets that are taking wiring from the vehicle to the underhood area. That is going to be the best place to find something already there that hopefully will work. Otherwise you would have to drill a hole in the firewall, install appropriate size grommet in that hole and then run the power cable through that.

expert reply by: Jameson C

Jameson C.

1/27/2026

Hey Karen, how did things go with routing the cord for your Kat’s interior heater through the RAV4’s firewall? Your update could make it easier for others trying to run wiring for similar heaters.

Karen P.

1/27/2026

@JamesonC I ran a 12 gauge cord through a vehicle door then plugged the heater into it. Closed the door on the extension cord. The weatherstripping protected it from being crushed. Ran the heater on a timer and checked it to make sure nothing was overheating. Worked fine. Got this tip from my son who asked a couple of other employees at his workplace who had internal vehicle heaters.