Wiper Motor: Description and Operation
REAR WIPER MOTORFig. 18 Rear Wiper Motor:
The rear wiper motor is concealed behind a molded plastic trim cover on the inside of the liftglass near the right liftglass hinge at the top of the glass. A large blackout area of the liftglass conceals the unit from the exterior of the vehicle. The end of the motor output shaft that protrudes through a large rubber grommet in the liftglass to drive the rear wiper arm and blade is the only visible component of the rear wiper motor. A large flat washer and a nut secure and seal the motor output shaft to the outside of the liftglass, while a rubber insulator in a slot on the outboard upper corner of the motor bracket is secured by a stud and nut to the inside of the lift- glass near the right liftglass hinge. The connector of a short pigtail harness is secured to a tab on the back of the motor bracket, and connects the rear wiper motor to the vehicle electrical system through a dedicated take out and connector of the hardtop wire harness. The rear wiper motor consists of the following major components:
- Bracket - The rear wiper motor bracket consists of a stamped steel mounting plate that is secured with screws to the wiper motor and transmission. A rubber insulator in a slot on the upper outboard corner of the bracket is secured by a nut and washer to a stud on the inside surface of the liftglass. An integral tab on the back of the bracket supports the wiper motor pigtail wire connector.
- Motor - The single-speed permanent magnet rear wiper motor is secured with screws to the rear wiper motor bracket. The wiper motor includes an integral transmission, a motor output shaft, a diode, and the rear wiper motor park switch.
The rear wiper motor cannot be adjusted or repaired. If any component of the motor is faulty or damaged, the entire rear wiper motor unit must be replaced. The motor output shaft grommet, washer and nut are available for individual service replacement.
The rear wiper motor operation is controlled by the vehicle operator through battery current inputs received by the rear wiper motor from the rear wiper and washer switch on the instrument panel, and the rear wiper motor park switch, which control current flow to the wiper motor brushes. An internal diode protects the motor from feedback through the park switch when the switch is closed to the fused ignition switch output (run) circuit. An internal circuit breaker protects the motor from overloads.
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 motor brush to the rear wiper and washer switch output or to a fused ignition switch output (run) circuit, depending upon the position of the wiper 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 blade in the uppermost portion of the wipe pattern.
The wiper motor transmission converts the rotary output of the wiper motor to the back and forth wiping motion of the rear wiper arm and blade on the liftglass. The rear wiper motor may be diagnosed using conventional diagnostic tools and methods.