Seat Temperature Relay: Description and Operation

Heated Seat Relay:

The heated seat relay is an electromechanical device that switches battery current to the heated seat module when the relay control coil is energized. The heated seat relay is located in the Junction Block (JB), on the left end of the instrument panel in the passenger compartment. The heated seat relay is a International Standards Organization (ISO) micro-relay. Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions. The ISO micro-relay terminal functions are the same as a conventional ISO relay. However, the ISO micro-relay terminal pattern (or footprint) is different, the current capacity is lower, and the physical dimensions are smaller than those of the conventional ISO relay.

The heated seat relay cannot be repaired or adjusted and, if faulty or damaged, it must be replaced.

The ISO relay consists of an electromagnetic coil, a resistor or diode, and three (two fixed and one movable) electrical contacts. The movable (common feed) relay contact is held against one of the fixed contacts (normally closed) by spring pressure. When the electromagnetic coil is energized, it draws the movable contact away from the normally closed fixed contact, and holds it against the other (normally open) fixed contact. when the electromagnetic coil is de-energized, spring pressure returns the movable contact to the normally closed position. The resistor or diode is connected in parallel with the electromagnetic coil in the relay, and helps to dissipate voltage spikes that are produced when the coil is de-energized.

The heated seat relay is controlled by the premium version of the Central Timer Module (CTM), which controls the ground feed to the coil ground terminal of the relay to energize and de-energize the electromagnetic coil of the relay. The CTM monitors engine operation through messages it receives from the Powertrain Control Module (PCM) over the Chrysler Collision Detection (CCD) data bus network. The CTM is programmed to energize the relay only when the engine is running, and to de-energize the relay when the engine is not running. Refer to Central Timer Module for the location of more information on the premium CTM.