It's a corded electrical element, and the cord typically exits the engine compartment through a grommet in the firewall or near the oil pan. You'll likely see a heavy-duty cord plugged into it if it's installed.
Because of the variations, visually inspecting your engine is the most reliable way to locate it. Look closely near the bottom of the passenger side of the engine block. If you're unsure, consulting your owner's manual or a repair manual specific to your year and model Dodge 1500 is highly recommended.