2000 TM electric water heater switch location

I called the factory but the service dept had closed. I think it was Adam in parts that told me that the switch to heat water with electric not propane is "underneath" and has a cotter pin in it. The manual also refers to the switch and cotter pin.

Under the outside panel is the wheel well.

I cannot find it. I must be looking in the wrong places.

The switch inside I believe is for the propane. Right?

HELP!!!!!!

God bless, Frank