Mercedes-Benz Sprinter / Dodge Sprinter. Manual - part 255

RAIN SENSOR CONTROL MOD-
ULE

DESCRIPTION

The Rain Sensor Control Module (RSCM) is the

primary component of the automatic wiper system
(Fig. 11). The RSCM is secured with two screws and
nuts to a bracket located under the instrument panel
above the throttle pedal within the passenger com-
partment. The rectangular molded plastic housing of
the RSCM has an integral mounting tab on each side
and an integral connector receptacle on one end,
which contains the module terminal pins. These ter-
minal pins connect the RSCM to the vehicle electrical
system through a dedicated take out and connector of
the instrument panel wiring. Concealed and pro-
tected within the RSCM housing is the electronic cir-
cuitry of the module.

The RSCM cannot be repaired and, if damaged or

faulty, the entire module must be replaced.

OPERATION

The microprocessor-based Rain Sensor Control

Module (RSCM) is only used in vehicles equipped
with an optional automatic wiper system. The RSCM
monitors inputs from the ignition switch, the wiper
and washer switch circuitry of the multi-function
switch on the steering column, the park switch
within the wiper motor, and the rain sensor on the
inside of the windshield glass. Based upon these
inputs the RSCM sends the proper control outputs to
the wiper motor and the washer pump motor to pro-
vide all of the requested wiper and washer system
functions.

The RSCM operates on battery current received

from a fuse in the fuse block on a fused ignition
switch output (run-start) circuit so that the RSCM
will operate whenever the ignition switch is in the
On or Start positions. The RSCM receives ground at
all times through its connection to the instrument
panel wire harness. It is important to note that the
default condition for the wiper system is automatic
wipers Off; therefore, if no input is received from the
rain sensor by the RSCM, the automatic wipers will
be disabled and the RSCM will default the wiper and
washer system to normal manual operation for con-
tinuous low or high speed wiper or washer mode.

The hard wired RSCM circuits may be diagnosed

using conventional diagnostic tools and methods.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the internal cir-
cuitry of the RSCM. Refer to the appropriate wiring
information.

REMOVAL

WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental

restraint

system

before

attempting

any

steering wheel, steering column, airbag, seat belt
tensioner, or instrument panel component diagno-
sis or service. Disconnect and isolate the battery
negative (ground) cable, then wait two minutes for
the system capacitor to discharge before perform-
ing further diagnosis or service. This is the only
sure way to disable the supplemental restraint sys-
tem. Failure to take the proper precautions could
result in accidental airbag deployment.

(1) Disconnect and isolate the battery negative

cable.

(2) Locate the rain sensor control module on a

bracket under the instrument panel above the throt-
tle pedal (Fig. 12).

Fig. 11 Rain Sensor Control Module

1 - RAIN SENSOR CONTROL MODULE
2 - CONNECTOR RECEPTACLE
3 - MOUNTING TAB (2)

WIPERS/WASHERS

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(3) Cut the tie wrap on the control module (Fig.

13).

(4) Unlock and disconnect the wire harness con-

nector from the module connector receptacle.

(5) Remove the two screws and nuts that secure

the module to the bracket.

(6) Remove the module from the bracket.

INSTALLATION

WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental

restraint

system

before

attempting

any

(1) Position the rain sensor control module to the

bracket under the instrument panel above the throt-
tle pedal (Fig. 12).

(2) Install and tighten the two screws and nuts

that secure the module to the bracket (Fig. 13).

(3) Reconnect and lock the wire harness connector

to the module connector receptacle.

(4) Install a new tie wrap to secure the wire har-

ness to the control module.

(5) Reconnect the battery negative cable.

WASHER FLUID LEVEL
SWITCH

DESCRIPTION

The optional washer fluid level switch is a single

pole, single throw switch that is integral to a unique
version of the washer pump/motor unit, located rear-
ward facing side of the washer reservoir, which is
located in a dedicated hole on the top of the sump
area near the back of the windshield washer reser-
voir on the right front fender wheel house in the
engine compartment. Only a molded plastic nipple
with a clear vent tube are visible near the top of the
washer pump/motor unit that is equipped with the
optional fluid level switch when it is installed in the
reservoir. The vent tube is routed to and retained in
an integral clip located behind the reservoir filler cap
near the top of the reservoir. This version of the
washer pump/motor unit also has a third terminal
pin in its integral connector receptacle. The washer
fluid level switch cannot be adjusted or repaired. If
faulty or damaged, the entire washer pump/motor
unit must be replaced.

OPERATION

The washer fluid level switch monitors the level of

the washer fluid in the washer reservoir. When the
fluid level in the washer reservoir is at or above the
predetermined minimum, the switch contacts are
open. When the fluid level in the washer reservoir

Fig. 12 Rain Sensor Control Module Location

1 - INSTRUMENT PANEL
2 - RAIN SENSOR CONTROL MODULE
3 - THROTTLE PEDAL

Fig. 13 Rain Sensor Control Module Remove/Install

1 - SCREW (2)
2 - CONNECTOR
3 - NUT (2)
4 - TIE WRAP
5 - MODULE

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WIPERS/WASHERS

falls below the predetermined minimum, the switch
contacts of the normally open switch close. The
washer fluid level switch is connected to the vehicle
electrical system through the washer pump/motor
unit take out and connector of the vehicle wire har-
ness. The switch receives a path to ground at all
times through another take out of the vehicle wire
harness with a single eyelet terminal connector that
is secured under a ground screw located near the
right headlamp in the engine compartment.

The switch is connected in series between ground

and the washer fluid switch sense input to the Elec-
troMechanical Instrument Cluster (EMIC). When the
switch closes, the EMIC senses the ground on the
washer fluid switch sense circuit. The EMIC is pro-
grammed to respond to this input by illuminating the
washer fluid indicator. The washer fluid level switch
input to the EMIC may be diagnosed using conven-
tional diagnostic tools and methods.

WIPERS/WASHERS

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WASHER HOSES / TUBES

DESCRIPTION

The washer plumbing consists of a small diameter

rubber hose that is routed from the barbed outlet
nipple of the washer pump/motor on the washer res-
ervoir to the check valve just below the cowl top
panel behind the rear of the hood opening in the
engine compartment (Fig. 14). The other two barbed
nipples of the check valve are connected to two short
lengths of hose that each terminate at a molded plas-
tic elbow that passes through a rubber grommet from
the engine compartment to the outside of the cowl
top panel near each wiper pivot. The two washer noz-
zle hoses are then connected from the elbow fittings
on the outside of the cowl top panel along the under-
side of the wiper arms to the two washer nozzles.

Washer hose is available for service only as roll

stock, which must then be cut to length. The molded
plastic washer hose fittings cannot be repaired. If
these fittings are faulty or damaged, they must be
replaced.

OPERATION

Washer fluid in the washer reservoir is pressurized

and fed by the washer pump/motor through the
washer system plumbing and fittings to the two
washer nozzles. Whenever routing the washer hose

or a wire harness containing a washer hose, it must
be routed away from hot, sharp, or moving parts;
and, sharp bends that might pinch the hose must be
avoided.

WASHER NOZZLE

DESCRIPTION

Fig. 14 Washer Plumbing

1 - WASHER SUPPLY HOSE

4 - ELBOW FITTING (2)

2 - CHECK VALVE

5 - WIPER ARM WASHER HOSE (2)

3 - WASHER NOZZLE HOSE (2)

6 - WASHER RESERVOIR

Fig. 15 Washer Nozzle

1 - WASHER NOZZLE
2 - NIPPLE
3 - ORIFICE (3)

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WIPERS/WASHERS

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