Durango 2WD V8-4.7L Flex Fuel (2009)
The rear wiper relay is a conventional International Standards Organization (ISO) micro relay. Relays conforming to the ISO specifications have
common physical dimensions, current capacities, terminal patterns, and terminal functions. This relay is contained within a small, rectangular, molded
plastic housing and is connected to all of the required inputs and outputs through five integral male spade-type terminals that extend from the relay base
plate.
The rear wiper relay is located in the Power Distribution Center (PDC) in the engine compartment near the battery. Refer to the layout label on the
underside of the PDC cover for specific relay cavity assignment information.
The rear wiper relay cannot be adjusted or repaired and, if ineffective or damaged, the unit must be replaced.
Rear Wiper Relay - Operation
OPERATION
The rear wiper relay is an electromechanical switch that uses a low current input from the Front Control Module (FCM) to control a high current output
to the rear wiper motor. The movable common feed contact point is held against the fixed normally closed contact point by spring pressure. When the
relay coil is energized, an electromagnetic field is produced by the coil windings. This electromagnetic field draws the movable relay contact point away
from the fixed normally closed contact point, and holds it against the fixed normally open contact point. When the relay coil is de-energized, spring
pressure returns the movable contact point back against the fixed normally closed contact point. A resistor is connected in parallel with the relay coil in
the relay, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil
collapses.
The rear wiper relay terminals are connected to the vehicle electrical system through a connector receptacle in the Power Distribution Center (PDC). The
inputs and outputs of the rear wiper relay include:
-
Common Feed Terminal - The common feed terminal (30) is connected to the rear wiper motor through the rear wiper motor control circuit.
When the rear wiper relay is de-energized, the common feed terminal is connected to ground. When the rear wiper relay is energized, the common
feed terminal of the relay is connected to battery current from a fuse in the Power Distribution Center (PDC) through a fused B(+) circuit.
-
Coil Ground Terminal - The coil ground terminal (85) is connected to the relay control output of the FCM through the rear wiper relay control
circuit. The FCM controls the ground path for this circuit internally to energize or de-energize the rear wiper relay based upon its programming,
rear wiper and washer request messages received from the Electro mechanical Instrument Cluster (EMIC) over the Controller Area Network
(CAN) data bus, and a hard wired input from the rear wiper motor park switch.
-
Coil Battery Terminal - The coil battery terminal (86) is connected to battery current from a fuse in the PDC through a fused B(+) circuit at all
times.
-
Normally Open Terminal - The normally open terminal (87) is connected to battery current from a fuse in the PDC through a fused B(+) circuit
at all times.
-
Normally Closed Terminal - The normally closed terminal (87A) is connected to ground at all times.
The rear wiper relay as well as the hard wired inputs and outputs of the relay may be diagnosed using conventional diagnostic tools and procedures.
Refer to the appropriate wiring information.
