How do you wire remote thermometer through firewall?

I'd like to add an inside/outside thermometer but can't figure out how to get a wire through the firewall to mount the "outside" sensor in front of the radiator. Any help would be greatly appreciated.

I have a 2010 access cab.

 

I took a sharp pocket knife and poked a hole through the wiring grommet under the brake vacuum chamber in my 2009 DC. Not sure your access cab is built the same. I have radio antenna coax cable and 2 N0. 10 wires coming through that hole.

 

Find any of the stuffing tubes that wires come thru already and tuck it thru there- or go buy a rubber grommet and put your own hole thru...

 

Thanks for the tips guys! I spent a lot of time looking at the stuff going through the firewall, including the bunch of wires in the area of the parking brake. I also pulled down the glovebox and gave that area a look. I would like to find an access point that already exists rather than making my own. I also saw underneath several rubber hole plugs under the plastic moulding right inside the driver's door. How do you get that plastic moulding out?

 

electrical tape a small wire to the tip of a straight metal clothes hanger. Makes it easy to slide through a firewall opening. I would go from the engine side and go through the same opening as the bundle of wires from the engine fuse box. You should be able to see it above the brake pedal area..

 

If you're talking about the door sills, just pull up on them. Start at the seam located right about where the front and rear suicide doors meet. Get your fingers under it and gently curl them to get the plastic clips to pop out.

Really I think your best option is to cut a small slit in the huge rubber grommet at the firewall, by the brake booster. I ran my oil temp/oil pressure and boost sensor wiring and hoses through a little 1/2" slit in this grommet.

 

Hmm...would you get a more accurate outside temp reading if you went through the grommet under the driver's side seat and put the sensor under the cab? If you pull up the door sill, you'll see wires under it. Some of these wires branch off and go under the driver's seat and then through the floor. There's a grommet there that you can put a small slit into. I ran bed light wiring through here.