Sprinter 2500 L5-2.7L DSL Turbo (2003)
Seat Heater Relay: Description and Operation
The heated seat relay is an electromechanical device that switches 12 v battery current to the heated seat elements when the relay control coil is
energized. The heated seat relay is located in the Fuse Block, under the drivers seat. The heated seat relay is a International Standards Organization
(ISO) relay. Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal
functions.
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.
