Relay-Heater Unit: Description
WARNING: This page is about a different car, the 2006 Dodge Magnum, 2006 Dodge Charger, and 2006 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
Three relays (1) are used for the electric positive temperature coefficient (PTC) heater system when equipped with the 3.0L diesel engine. The relays are International Standards Organization (ISO)-type relays. Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal functions and patterns (2). The PTC relays are electromechanical devices that switch fused battery current directly to the heating elements of the PTC heater unit as determined by the engine control module (ECM). The PTC relays are energized when provided a ground path by the ECM and the front control (FCM).
The three PTC relays are located in the diesel accessory fuse/relay block in the engine compartment.