GMC 4000 Series Service Manual page 30

Figure 6 — W iper Motor Installed (Conventional Cab)
may be restricted when motor is started, resulting
in a blown fuse. In any case when motor is first
started, be prepared to turn wiper switch off in the
event wiper arms were installed out of proper
sweep position. Reposition arms if necessary.
WIPER MOTOR REPLACEMENT
(CONV. CAB MODELS)
REMOVAL (Fig. 6)
1. Disconnect wiring harness at motor.
2. If windshield washers are used, disconnect
washer lines at pump.
3. Remove three screw assem blies which at­
tach motor assembly to front of cab cowl.
4. Pull motor forward from opening, then
through the opening, remove two nuts from arm-
to-link rod ball clamp to separate motor from link
rod. Remove motor assembly.
INSTALLATION (Figs. 6 and 7)
Before installing motor, scrape any of the old
sealing compound from around cowl opening, then
apply a bead of new compound around the opening.
Perform the installation procedures in the re­
verse of "Removal'' procedures.
IMPORTANT: Make sure motor ground strap
is free of paint before installing motor mounting
screws; otherwise motor will not operate. Also, be
sure that wiper motor crank arm is in "PARK"
position before attaching linkage and wiring harness.
WIPER MOTOR REPLACEMENT
(TILT CAB MODELS)
REMOVAL (Figs. 3 and 8)
1. Remove hex crown nut and lock washer
which attaches wiper arm to knurled driver and
G M C S E R V I C E M A N U A L
pivot shaft. Remove arm and driver.
steel washer, and leather washer from pivot shaft
housing.
at connector on motor drive unit. If equipped with
washers, disconnect hoses.
and drive unit to cab panel.
INSTALLATION (Figs. 3 and 8)
ing, then locate motor and drive unit to cab panel.
Attach unit mounting bracket to panel with four
cap screws and washers.
contact is made between panel and mounting bracket
so as to provide an electrical ground for motor.
drive unit. If equipped with washers, connect hoses.
hex nut, and rubber shield on pivot shaft housing.
Position arm driver on pivot shaft.
motor momentarily, then turn it off which should
rotate pivot shaft to "PARK" position (fig. 7).
located in the "PARK" position. Wet windshield,
then again operate wiper and check arm sweep.
Reposition arm on shaft driver if necessary. Se­
cure arm on shaft with crown nut.
WIPER TRANSMISSION LINKAGE AND
MOUNTING BRACKET REPLACEMENT
REMOVAL (Fig. 8)
GENERAL MAINTENANCE
2. Remove rubber rainshield, hex nut, flat
3. Inside of cab, disconnect electrical wiring
4. Remove four cap screws which attach motor
1. Position styrofoam pad on pivot shaft hous­
IMPORTANT: Be sure a good metal-to-m etal
2. Connect electrical wiring to terminals on
3. Install leather washer, flat steel washer,
4. Before installing wiper arms, operate wiper
5. Install arm on driver of shaft so that it is
(TILT CAB MODELS)
1. Remove small retaining ring near end of
Sec. 1
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