Grand Cherokee 4WD V6-3.0L DSL Turbo (2008)
Auxiliary Heater Element Relay: Description and Operation
Description
DESCRIPTION
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 power distribution center (PDC) in the engine compartment.