Dodge Dakota Sport 2001 Service Manual page 572

AN
WIPERS/WASHERS (Continued)
When the ignition switch is in the Accessory or On
positions, battery current from a fuse in the Junction
Block (JB) is provided through a fused ignition
switch output (run-acc) circuit to the wiper motor
park switch, the wiper relay, and the multi-function
switch. The internal circuitry of the multi-function
switch provides a direct hard wired battery current
output to the low speed or high speed brushes of the
wiper motor when the Lo or Hi switch setting is
selected, which causes the wipers to cycle at the
selected speed. The intermittent wipe, and wipe-af-
ter-wash features of the wiper and washer system
are provided by the electronic intermittent wipe logic
circuit within the Central Timer Module (CTM). In
order to provide the intermittent wipe feature, the
CTM monitors the wiper switch state and the wiper
motor park switch state. In order to provide the
wipe-after-wash feature, the CTM monitors both the
washer switch state and the wiper motor park switch
state. When a Delay position is selected with the
multi-function switch control knob, the CTM logic cir-
cuit responds by calculating the correct delay inter-
val. The CTM then energizes the wiper relay by
pulling the relay control coil to ground. The ener-
gized wiper relay directs battery current through the
normally open contact of the relay back through the
internal Delay position circuitry of the multi-function
switch to the low speed brush of the wiper motor.
The CTM monitors the wiper motor operation
through the wiper park switch sense circuit, which
allows the CTM to determine the proper timing to
begin the next wiper blade sweep. The normal delay
intervals are driver adjustable from about one-half
second to about eighteen seconds.
The CTM also provides a speed sensitive intermit-
tent wipe feature. By monitoring vehicle speed mes-
sages received from the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus network, the CTM is able to
adjust the delay intervals to compensate for vehicle
speed. Above about sixteen kilometers-per-hour (ten
miles-per-hour) the delay is driver adjustable from
about one-half second to about eighteen seconds.
Below about sixteen kilometers-per-hour (ten miles-
per-hour) the delay times are doubled by the CTM,
from about one second to about thirty-six seconds.
When the Off position of the multi-function switch
wiper control knob is selected, one of two events is
possible. The event that will occur depends upon the
position of the wiper blades on the windshield at the
moment that the Off position is selected. If the wiper
blades are in the down position on the windshield
when the Off position is selected, the park switch
that is integral to the wiper motor is closed to ground
and the wiper motor ceases to operate. If the wiper
blades are not in the down position on the windshield
at the moment the Off position is selected, the park
switch is closed to battery current through a fused
ignition switch output (run-acc) circuit. The park
switch sense circuit directs this battery current to
the low speed brush of the wiper motor through the
normally closed contact of the wiper relay and the
internal Off position circuitry of the multi-function
switch. This causes the wiper motor to continue run-
ning until the wiper blades are in the down position
on the windshield and the park switch is again
closed to ground.
When the Wash position of the multi-function
switch is selected, the Wash position circuitry within
the switch directs a battery current signal input to
the CTM. The CTM monitors the washer switch state
through this input to control a battery current output
to the washer pump/motor unit. When the washer
switch is closed with the wiper system turned Off,
the CTM operates the wiper motor through the wiper
relay in the same manner as it does to provide the
Delay mode operation. After the state of the washer
switch changes to open, the CTM monitors the wiper
motor through the wiper park switch sense circuit,
which allows the CTM to monitor the number of
wiper blade sweeps. After the appropriate number of
wiper sweeps, the CTM de-energizes the wiper relay
and the wipers return to their park position.
Proper testing of the CTM, the PCM, or the PCI
data bus vehicle speed messages requires a DRBIII
scan tool. Refer to the appropriate diagnostic infor-
mation. Refer to the owner's manual in the vehicle
glove box for more information on the features and
operation of the wiper and washer system.
DIAGNOSIS AND TESTING - WIPER &
WASHER SYSTEM
WIPER SYSTEM
The diagnosis found here addresses an electrically
inoperative wiper system. If the wiper motor oper-
ates, but the wipers do not move on the windshield,
replace the faulty wiper module. If the wipers oper-
ate, but chatter, lift, or do not clear the glass, clean
and inspect the wiper
required. (Refer to 8 - ELECTRICAL/WIPERS/
WASHERS - INSPECTION) and (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS - CLEANING). Refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
The following tests will help to diagnose the hard
wired components and circuits of the wiper system.
However, these tests may not prove conclusive in the
WIPERS/WASHERS
system components
8R - 3
as