Dodge ZB 2005, Service Manual

Page: 272 / 1873

common physical dimensions, current capacities, ter-
minal functions and patterns. 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 capac-
ity is lower, and the physical dimensions are smaller
than those of the conventional ISO relay. The EBL
relay is a electromechanical device that switches bat-
tery current through a fuse in the power distribution
center (PDC) to the rear window defogger grid. The
EBL relay is energized when the relay coil is pro-
vided a ground path by the control circuitry within
the A/C-heater control.
The EBL relay is located in the PDC in the engine
compartment.
OPERATION
The ISO-standard rear window defogger (EBL)
micro-relay is an electromechanical switch that uses
a low current input controlled by the A/C-heater con-
trol 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 pres-
sure 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 electromag-
netic interference that can be generated as the elec-
tromagnetic field of the relay coil collapses.
The EBL relay terminals are connected to the vehi-
cle electrical system through a receptacle in the
power distribution center (PDC). The inputs and out-
puts of the EBL relay include:
•
The common feed terminal (86) receives a bat-
tery current input from a fuse in the PDC through a
fused B(+) circuit at all times.
•
The coil ground terminal (83) receives a ground
input from the A/C-heater control when the A/C-
heater control electronically pulls the control circuit
to ground.
•
The coil battery terminal (85) receives a battery
current input from the body control module (BCM)
only when the ignition switch is in the Run position.
•
The normally open terminal (82) provides a bat-
tery current output to the rear window defogger
through the relay output circuit only when the rear
window defogger relay coil is energized.
•
The normally closed terminal (82A) is not con-
nected to any circuit in this application, but provides
a battery current output only when the rear window
defogger relay coil is de-energized.
The EBL micro-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 micro-relay and for com-
plete rear window defogger (EBL) wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the cover from the power distribution
center (PDC) (Fig. 5) located in the engine compart-
ment.
NOTE: Refer to the fuse and relay layout map on
the inside of the PDC cover for EBL relay location.
(3) Remove the EBL relay from the PDC.
INSTALLATION
NOTE: Refer to the fuse and relay layout map on
the inside of the power distribution center (PDC)
cover for EBL relay location.
(1) Position the EBL relay into the proper recepta-
cle of the PDC located in the engine compartment.
(2) Align the EBL relay terminals with the termi-
nal cavities in the PDC receptacle and push down
firmly on the relay until the terminals are fully
seated.
Fig. 4 Rear Window Defogger Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
ZB
HEATED SYSTEMS 8G - 3
REAR WINDOW DEFOGGER RELAY (Continued)