Grand Cherokee 4WD V8-5.7L (2008)
Wiper Motor: Description and Operation
Wiper Module
Description
DESCRIPTION
The front wiper module is secured to the cowl plenum panel beneath the cowl plenum cover/grille panel. The ends of the wiper pivot shafts protrude
through dedicated openings in the cowl plenum cover/grille panel to drive the wiper arms and blades and are the only visible components of the front
wiper module.
The wiper module consists of the following major components:
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Bracket - The wiper module bracket (1) consists of a long tubular steel main member that has a stamped pivot bracket formation near each end
where the two wiper pivots (2) are secured. The wiper module bracket is secured within the cowl plenum by two screws and a stud and nut through
three rubber insulators (3). A stamped steel mounting plate (6) for the wiper motor (4) is secured with welds near the center of the main member.
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Crank Arm - The wiper motor crank arm (5) is a stamped steel unit with an internally splined hole on the driven end that is secured to the wiper
motor output shaft with a nut, and has a long ball stud secured to the drive end to accept the wiper linkage. The crank arm is serviced only as a unit
with the front wiper motor.
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Linkage - Two stamped steel drive links (7) connect the wiper motor crank arm to the wiper pivot lever arms (8). The right side drive link has a
plastic socket-type bushing on each end. The left side drive link has a plastic socket-type bushing on one end, and a plastic sleeve-type bushing on
the other end. The socket-type bushing on one end of each drive link is snap-fit over the ball stud on the lever arm of its respective pivot. The left
side drive link sleeve-type bushing end is then snap-fit over the motor crank arm ball stud, and the other socket-type bushing of the right side drive
link is snap-fit over the exposed end of the wiper motor crank arm ball stud.
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Motor - The wiper motor is secured with three screws to the motor mounting plate near the center of the wiper module bracket. The wiper motor
output shaft passes through a hole in the mounting plate, where a nut secures the wiper motor crank arm to the motor output shaft. The two-speed
permanent magnet wiper motor features an integral transmission, an internal park switch, and an internal Positive Temperature Coefficient (PTC)
circuit breaker. The front wiper motor with crank arm are serviced independently from the remainder of the front wiper module.
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Pivots - The two front wiper pivots are secured to the ends of the wiper module bracket. The lever arms that extend from the bottom of the pivot
shafts each have a ball stud on their end. The upper end of each pivot shaft where the wiper arms will be fastened is tapered and serrated with a
threaded stud formation at the tip.
The front wiper module cannot be adjusted or repaired. The front wiper motor and crank arm is serviced independent of the front wiper module. If any
other component of the module is ineffective or damaged, the entire front wiper module unit must be replaced.
Operation
OPERATION
The front wiper module operation is controlled by the battery current inputs received by the wiper motor through the wiper on/off and wiper high/low
relays. The wiper motor speed is controlled by current flow to either the low speed or the high speed set of brushes. The park switch is a single pole,
single throw, momentary switch within the wiper motor that is mechanically actuated by the wiper motor transmission components. The park switch
alternately closes the wiper park switch sense circuit to ground or to battery current, depending upon the position of the wipers on the glass. This feature
allows the motor to complete its current wipe cycle after the wiper system has been turned OFF, and to park the wiper blades in the lowest portion of the
wipe pattern. The automatic resetting circuit breaker protects the motor from overloads.
