RAI N SEN SOR
DESCRIPTION
The ra in sensor pr ovides th e pr imary in pu t for the
opt ional aut omatic wiper syst em (F ig. 6). The rain
sensor is located on the inside of the windshield,
where it is con cealed with in the molded plastic trim
cover t hat snaps over the base of the rea r view m ir-
ror arm. Th e sensor fits with in the cent er of a rin g-
like molded plastic bracket t hat is glued to the inside
of th e windshield glass and tha t also serves as the
su pport for the rear view mirror.
The rain sensor is contain ed within a circular
molded bla ck plastic hou sing with a sh ort pigtail
wire an d a con nector insu lator containing th ree ter-
minal cavities that exits one side of th e hou sing. This
pigtail conn ects t he r ain sensor to the vehicle electri-
cal system th rough a dedicated ta ke out and conn ec-
tor of t he overh ead wire har ness that extends from
above the hea dliner. A m olded pla st ic trou gh rou tes
and con ceals t he pigta il wires on the inside of the
windshield between the rear view mirror base an d
the headliner.
The windshield side of th e rain sensor hou sing is
open, but covered with a clea r gelatin-like materia l
that protect s the int erna l electr onic sensor circu itry
and serves as the lens for t he InfraRed (IR) diodes
and photocells within the sensor h ousing. Th is gel
coating must never be touch ed or th e ra in sensor
function m ay be im pa ired and the unit ren dered
unusable. The rain sensor cannot be adjusted or
repaired a nd, if da maged or fau lty, the entire sensor
must be repla ced. The sensor bracket a nd a rea r view
mirror adhesive kit are available for separa te service
repla cement .
OPERATION
The r ain sensor opera tes on ba tter y cur rent and a
clean gr ound received from th e r ain sensor contr ol
module. The rain sensor con tains In fraRed (IR)
diodes that dir ect IR light beams a t the windshield
at an angle. When th e windshield glass is dry, most
of this IR light is r eflected back to the sensor, which
uses ph otocell receivers to measure the intensity of
the light . Wh en moistur e accumulates on t he wind-
sh ield glass, mu ch of the IR light is refr acted awa y
from the phot ocell r eceivers. This cau ses changes in
the signa l outpu t of the ra in sensor. Th e r ain sensor
control module mon itors the signal output from the
sensor and then cont rols the wiper motor speed and
wipe interva ls accordingly.
It is import ant t o n ote th at th e default condition
for the wiper system is autom atic wipers Off; th ere-
fore, if no message is received from the rain sensor
by th e r ain sensor cont rol modu le, th e a utomatic wip-
ers will be disabled. If automatic wiper s ar e disa bled,
normal low and high speed con tinuous wiper opera-
tion ar e unaffect ed. Also, due t o th e low voltage
nature of th e rain sensor signal an d the impa ct that
minor flu ctuations in th is signal strength can have
on wiper operat ion, grou nded shielding circuits are
pr ovided at the roof and contr ol module connectors to
control electr ical induction into the sensor signal cir-
cuit.
The har d wired rain sensor circu its may be diag-
nosed u sing convent ional diagnostic tools an d met h-
ods. However, conventional diagn ost ic meth ods m ay
not prove conclusive in the dia gnosis of the internal
circuitry or the optics of th e r ain sen sor. Refer to the
appropriate wiring infor mation.
STAN DARD PROCEDU RE
RAIN SENSOR BRACKET REPLACEMENT
The r ain sensor fit s with in th e cent er of a ring-like
molded pla st ic bracket that is glued to the inside of
the windshield glass and that also serves as the sup-
por t for t he r ear view mirror arm. If th e bracket
sh ould come loose from the win dshield, it m ust be
rein st alled using a rear view mir ror a dh esive kit and
the pr ocedu re that follows.
Fig. 6 Rain Sensor
1 - HEADLINER
2 - TROUGH
3 - WINDSHIELD
4 - RAIN SENSOR
5 - MIRROR
8R - 12 WIPERS/WASHERS VA
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