Wiper On/Off Relay Description; Operation - Dodge dakota 2002 Service Manual

DR
WIPER ON/OFF RELAY
DESCRIPTION
Fig. 27 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
The wiper on/off relay is located in the Integrated
Power Module (IPM) in the engine compartment near
the battery. The wiper on/off relay is a conventional
International Standards Organization (ISO) micro
relay (Fig. 27). Relays conforming to the ISO specifi-
cations have common physical dimensions, current
capacities, terminal patterns, and terminal functions.
The relay is contained within a small, rectangular,
molded plastic housing and is connected to all of the
required inputs and outputs by five integral male
spade-type terminals that extend from the bottom of
the relay base.
The wiper on/off relay cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.

OPERATION

The wiper on/off relay is an electromechanical
switch that uses a low current input from the Front
Control Module (FCM) to control a high current out-
put to the 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.
WIPERS/WASHERS
The wiper on/off relay terminals are connected to
the vehicle electrical system through a connector
receptacle in the Integrated Power Module (IPM).
The inputs and outputs of the wiper on/off relay
include:
• Common Feed Terminal - The common feed
terminal (30) is connected to the common feed termi-
nal of the wiper high/low relay at all times through
the wiper on/off relay output circuit.
• Coil Ground Terminal - The coil ground termi-
nal (85) is connected to a control output of the Front
Control Module (FCM) through a wiper on/off relay
control circuit. The FCM controls wiper motor opera-
tion by controlling a ground path through this cir-
cuit.
• Coil Battery Terminal - The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the IPM through a fused ignition switch
output (run-acc) circuit.
• Normally Open Terminal - The normally open
terminal (87) receives battery current at all times
from a fuse in the IPM through a fused ignition
switch output (run-acc) circuit, and provides battery
current to the wiper on/off relay output circuit when-
ever the relay is energized.
• Normally Closed Terminal - The normally
closed terminal (87A) is connected to ground at all
times through a take out of the left headlamp and
dash wire harness with an eyelet terminal connector
that is secured by a screw to the front end sheet
metal, and is connected to the wiper on/off relay out-
put circuit whenever the relay is de-energized.
The wiper on/off relay may be diagnosed using con-
ventional diagnostic tools and methods. However,
conventional diagnostic methods may not prove con-
clusive in the diagnosis of the instrument cluster, the
Front Control Module (FCM), or the electronic mes-
sage inputs to or outputs from the instrument cluster
and the FCM that control the operation of the wiper
on/off relay. The most reliable, efficient, and accurate
means to diagnose the wiper on/off relay, the instru-
ment cluster, the FCM, or the electronic message
inputs and outputs related to the wiper on/off relay
operation requires the use of a DRBIII
Refer to the appropriate diagnostic information.
8R - 25
scan tool.