2004 Toyota Tundra Owners Manual - Page 188
2004 Toyota Tundra Manual
Page 188 highlights
'04 TUNDRA_U (L/O 0309) Never use the switch for normal engine starting. Be sure to follow the starting procedure instructed in "How to start the engine" in Section 3. 188 2004 TUNDRA from Sep. '03 Prod. (OM34426U)