Grand Caravan V6-3.3L VIN R (2005)
Rear Defogger Relay: Description and Operation
Rear Window Defogger (EBL) Relay
The rear window defogger (EBL) relay is a International Standards Organization (ISO)-type relay. Relays conforming to the ISO specifications have
common physical dimensions, current capacities, terminal functions and patterns. The EBL relay is a electromechanical device that switches battery
current through a fuse in the integrated power module (IPM) to the rear window defogger grid and switches battery current through a positive thermal
coefficient (PTC) in the IPM to the outside mirror heating grids. The EBL relay is energized when the relay coil is provided a ground path by the control
circuitry within the front control module (FCM).
The ISO-standard rear window defogger (EBL) relay is an electromechanical switch that uses a low current input controlled by the front control module
(FCM) to control the high current output to the rear window defogger grid lines. The movable, common feed relay contact is held against the fixed,
normally closed relay contact by spring pressure. When the electromagnetic relay coil is energized, it draws the movable common feed relay contact
away from the fixed, normally closed relay contact and, holds it against the fixed, normally open relay contact. This action allows high current to flow to
the rear window defogger grid lines.
When the relay coil is de-energized, spring pressure returns the movable relay contact back against the fixed, normally closed contact point. The resistor
or diode is connected in parallel with the relay coil, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the
electromagnetic field of the relay coil collapses.
The EBL relay cannot be repaired and, if faulty or damaged, it must be replaced. Refer to the appropriate wiring information for diagnosis and testing of
the ISO-standard relay and for complete rear window defogger (EBL) wiring diagrams.
