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8R - 4
WIPERS/WASHERS
WIPERS/WASHERS (Continued)
The vehicle operator initiates all wiper and washer
system functions with the multi-function switch
wiper control stalk that extends from the right side
of the steering column, just below the steering wheel.
Depressing, raising, or pulling the right control stalk
of the multi-function switch selects the desired wiper
system operating mode (Fig. 2). The wiper system
allows the vehicle operator to select from two contin-
uous wiper speeds, Hi or Lo, a fixed interval inter-
mittent wipe mode, and a pulse wipe mode. Pushing
the knob on the end of the control stalk towards the
steering column activates the washer pump/motor,
which dispenses washer fluid onto the windshield
glass through the washer nozzles.
Fig. 2 Windshield Wiper/Washer Switch
1 - INTERMITTENT WIPE MODE
2 - CONTINUOUS LOW SPEED WIPE MODE
3 - CONTINUOUS HIGH SPEED WIPE MODE
4 - WASHER MODE
5 - PULSE WIPE MODE
When the ignition switch is in the On position, bat-
tery current from a fuse in the fuse block underneath
the steering column is provided through a fused igni-
tion switch output circuit to the wiper motor park
switch, the intermittent wipe logic circuitry of the
wiper, turn signals and engine start control module
within the fuse block, 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, Hi, or Pulse
position is selected, which causes the wipers to cycle
at the selected speed for as long as that switch posi-
tion remains selected.
In order to provide the intermittent wipe and wipe-
after-wash features, the intermittent wipe logic cir-
cuitry within the fuse block monitors inputs from the
intermittent wipe and washer switch circuitry of the
multi-function switch and the park switch in the
wiper motor. When the intermittent wipe position is
selected with the multi-function switch control stalk,
the intermittent wipe logic circuitry within the fuse
block responds by energizing the wiper relay and cal-
culating the correct delay interval. The energized
wiper relay directs battery current through the inter-
mittent wipe position circuitry of the multi-function
switch to the low speed brush of the wiper motor.
The intermittent wipe logic circuit monitors the
wiper motor operation through the wiper park switch
sense circuit, which allows it to determine the proper
timing to begin the next wiper blade sweep. The nor-
mal delay interval is about five seconds.
When the Off position of the multi-function switch
wiper control stalk 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, the intermittent wipe logic circuit de-ener-
gizes the wiper relay, 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 circuit. The
intermittent wipe logic circuit energizes the wiper
relay and the park switch sense circuit directs bat-
tery current to the low speed brush of the wiper
motor through the normally open contact of the
wiper relay, then through the internal Off position
circuitry of the multi-function switch. This causes the
wiper motor to continue running 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 control knob on the
right control stalk of the multi-function switch is
selected, the Wash position circuitry within the
switch directs a battery current signal input to the
washer pump motor, and to the intermittent wipe
logic circuitry. When the washer switch is closed with
the wiper system turned Off, the intermittent wipe
logic circuitry operates the wiper motor in the same
manner as it does to provide the intermittent wipe
mode operation. After the state of the washer switch
changes to open, the intermittent wipe logic circuitry
monitors the wiper motor through the wiper park
switch sense circuit, which allows it to monitor the
number of wiper blade sweeps. After the appropriate
number of wiper sweeps, the intermittent wipe logic
circuitry de-energizes the wiper relay once the wiper
motor returns the wipers to their park position.
The hard wired inputs to and outputs from the
wiper and washer system components may be diag-
nosed and tested using conventional diagnostic tools
VA
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