2004 Toyota Tundra Trailer Wiring | etrailer Lowest Price Trailer Wiring Guarantee. Installation instructions and lifetime expert support on all purchases of 2004 Toyota Tundra Trailer Wiring. Order online at etrailer or call 800-298-8924. 2004 Toyota Tundra Car Radio Wiring Diagram - ModifiedLife Whether your an expert Toyota Tundra mobile electronics installer, Toyota Tundra fanatic, or a novice Toyota Tundra enthusiast with a 2004 Toyota Tundra, a car stereo wiring diagram can save yourself a lot of time. Automotive wiring in a 2004 Toyota Tundra vehicles are becoming increasing more difficult to identify due to the installation of more advanced factory oem electronics.