Wipers Inoperative

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WIPERS INOPERATIVE (Be certain you have identified which wiper motor setup you have. There are several design changes and configurations across all years. Refer to the factory service manual for your exact application for best accuracy.


Turn ignition on and check for battery voltage at wiper motor terminal 2, Fig. 5, using a test lamp.
If lamp fails to light, proceed as follows:
Check wiper system fuse and replace if needed.
If fuse blows again, disconnect electrical connector to motor and replace fuse.
If fuse does not blow with harness disconnected, replace wiper motor.
If fuses continue to blow with harness disconnected, or if fuse was satisfactory in step ``a,'' repair feed circuit to wiper motor.
If lamp lights in step 1, check for battery voltage at motor terminal 1.
If lamp fails to light, check terminal board connections and repair as needed. If connections are satisfactory, motor is defective.
Place wiper switch in low position, disconnect electrical connector to gear box relay and connect test lamp between terminals 1 and 2 in connector.
If lamp fails to light, check continuity of wiring between motor and switch, switch continuity and ground, and repair as needed.
If lamp lights in step 5, place wiper switch in high position, disconnect electrical connector to pulse timer and connect test lamp between terminal 6 and timer connector and terminal 2 in gearbox relay connector.
If lamp fails to light, check continuity of wiring between motor and switch, switch continuity, and repair as needed.
If lamp lights in step 7, motor is defective.

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More information: Mounting bolts are 10-24 and one bushing should use a ground strap. The posts below contain more detail regarding wiper motors:

Permanent Magnet Motor

A permanent magnet type wiper is used on CK and G Series. The motor parts-field magnets, armature, drive gear etc. are enclosed in a two piece sheet metal housing. For purposes of explanation the housing halves are referred to as upper and lower housing. The two housings are attached to each other by ten extrusions which are staked over.

The wiper motor is protected by an automatic reset type circuit breaker located on the motor brush holder assembly. A fuse located in the fuse block protects the vehicle wiring.

The wiper motor can be operated only when the ignition switch is in the "run" or "accessory" position.

The wiper motor has three brushes; the "common" the low speed, and the high speed. When the ignition switch is "ON," power is applied to the common brush. The low speed and high speed brushes are connected to their respective ground via the control switch. When the control switch is positioned at "HI" or "LO" speed, a ground path is connected to the high or low speed brush in the motor. The motor runs at the switch selected speed.

In order to have the wiper blades stop in their normal park position and the wiper motor shut off properly, the motor must run in LO speed. When the control switch is moved to the OFF position, the low speed brush circuit goes through a park switch located in the gear housing and then to ground at the control switch. The park switch is normally closed and this allows the wiper to keep running. When the wiper blades reach their park position, the cam on the gear opens the normally closed park switch, which turns off the wiper.

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Round Motor

The 4-1/2 inch long, round motor assembly consists of an armature, field coil and end cap assembly, and a brush plate which fits over the armature and is connected to the field coils. The motor assembly is attached to a gearbox housing which also provides a mount for the washer pump. A worm gear on the armature commutator end drives the output shaft at a 90° angle through a drive gear and pawl assembly.
The gearbox assembly contains a magnet switch, relay and terminal board assembly (gearbox relay) which provides electrical connections and controls current flow through the motor. On standard (non-pulse) motors, Fig. 3, the two motor leads to the gearbox relay are concealed and routed through a cavity in the gear housing. On pulse type motors, Figs. 4 and 5, the two motor leads to the gearbox relay, and the feed wire to the pulse relay are exposed.

STANDARD (NON-PULSE) WIPER OPERATION
When ignition is on, battery voltage is supplied to gearbox relay terminal 2, Fig. 3. When terminal 1 is grounded, relay contacts close and current is supplied to the motor. Current flows through the series field to a splice where it is divided, and part passes through the armature to the motor housing ground, and part through the shunt field. Motor speeds are determined by the amount of current flowing through the shunt field.
Placing wiper switch in low position grounds gearbox relay terminals 1 and 3. The relay contacts close, shunt field current flows directly to ground at the switch through terminal 3, and the motor runs at low speed. Placing wiper switch in high grounds relay terminal 1, but terminal 3 remains open. Shunt field current flows to ground through a 20 ohm resistor connected between terminals 1 and 3, and the motor runs at a higher speed due to the weakened shunt field.
Placing wiper switch in off position opens the circuit to the gearbox relay magnet switch. This allows a spring loaded arm to move into the path of the output gear drive pawl, Fig. 6, while relay contacts remain closed. The shunt field is grounded through the wiper switch and the motor operates at low speed, allowing the gear mechanism to park the wipers and stop the motor.
As the output gear rotates, the drive pawl engages the latch arm on the gear box relay, and the output gear is unlocked from the drive pawl, lock pawl and drive plate. Since the output shaft and gear shaft are off center, continuing rotation causes a cam action which moves the drive pawl into a slot in the gearbox relay and allows wipers to move below their lowest point of normal travel. The drive pawl pushes the latch arm against the gearbox relay contacts, opening the contacts and stopping the motor in park position, Fig. 7.



PULSE WIPER OPERATION
Modified Pulse System
Models equipped with pulse wipers use a motor similar to the one used on standard wiper systems which has been modified to provide a delay wipe mode. In addition to standard wiper system components, the modified pulse system includes a voltage feed circuit to the wiper switch and a variable resistor in the switch, a pulse relay and holding switch mounted on the washer pump, and a timer circuit. The timer circuit, consisting of a capacitor, transistor and two diodes, is mounted in the washer pump or contained in a separate module.
The gearbox relay functions in a similar manner on both standard and pulse systems, but on pulse systems the gearbox relay supplies voltage to the pulse relay which controls current flow to the motor windings. In all wiper switch positions except delay, the gearbox and pulse relays are grounded simultaneously through the wiper switch, and the motor operates as outlined in ``Standard (Non-Pulse) Wiper Operation.'' When wiper switch is in delay position, pulse relay operation is controlled by the timer circuit.
Placing wiper switch in delay position grounds gearbox relay terminals 1 (relay) and 3 (shunt field) at the switch, and battery voltage is supplied to the timer circuit capacitor through the variable resistor in the switch. When the capacitor is fully charged, it activates the timer transistor. The transistor completes the pulse relay ground circuit, and current flows through the motor windings. As the motor begins to operate, holding switch contacts close, the capacitor discharges partially, and the pulse relay ground is maintained through the holding switch. As wipers complete their cycle, a fin on the washer pump drive cam opens the holding switch, Fig. 8. This stops the motor and allows the timer capacitor to recharge.
This cycle repeats as long as wiper switch is in delay position. Delay between wipe cycles is determined by controlling charging current to the capacitor through the switch resistor. Higher resistance produces longer delay.

Multiplex Wiper System
Models with pulse wiper use a motor similar to the one used on standard systems, but with modifications to provide a delay wipe mode. The multiplex system, while similar to earlier pulse wiper systems, uses an integrated circuit timer and the voltage feed to the wiper switch has been eliminated. In addition to standard wiper system components, the multiplex system uses a variable resistor in the wiper switch, a pulse relay and holding switch mounted in the washer pump, and a timer circuit. The timer, consisting of a capacitor and integrated circuit, is mounted on a circuit board in the washer pump or contained in a separate module.
The gearbox relay functions in a similar manner on both standard and multiplex systems. However, on pulse systems the gearbox relay supplies voltage to the pulse relay, current to the motor windings is controlled by the pulse relay, and voltage is supplied to the timer circuit from motor terminal 2. In all switch positions except delay, the gearbox relay, pulse relay and timer capacitor circuits are completed directly to ground through the wiper switch. This deactivates the timer circuit and allows the motor to operate as outlined in ``Standard (Non-Pulse) Wiper Operation.''
Placing wiper switch in delay position grounds gearbox relay terminals 1 (relay) and 3 (shunt field), and the timer capacitor is partially grounded through the variable resistor, allowing it to charge at a controlled rate. When the timer capacitor is fully charged it activates the integrated circuit. The integrated circuit completes the pulse relay ground circuit, and current flows through the motor windings.
As the motor begins to operate, holding switch contacts close, the capacitor discharges partially, and the pulse relay ground is maintained by the holding switch. As wipers complete their cycle, a fin on the washer pump drive cam opens the holding switch, Fig. 8, wipers stop and the timer capacitor begins to recharge. This cycle repeats as long as wiper switch is in delay position. Delay between wipes is determined by varying resistance between the timer capacitor and ground.

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Rectangular Motor

The rectangular motor, Fig. 1, consists of an armature, brush plate assembly, field coils and a housing which is attached to a gear housing. The motor electrical connections, park switch, and on some models a washer pump are also mounted on the gearbox. A gear on the commutator end of the armature drives an intermediate gear and pinion assembly, which in turn drives the output shaft. A crank arm on the output shaft operates wipers through a pivot link (transmission) assembly.
When ignition is on, battery voltage is supplied to motor terminal 2, Fig. 2. Current flows through the series field to a splice where it is divided, and part passes through the armature and part through the shunt field. The armature and shunt field circuits are completed to ground through the wiper switch, with motor speeds determined by resistance in the shunt field ground path.

Standard (Non-Pulse) Wiper Operation
Placing wiper switch in low position, grounds motor terminals 1 and 3, Fig. 2, at the wiper switch. Shunt field current flows directly to ground through terminal 3, armature current flows to ground through terminal 1 and the motor runs at low speed. Placing wiper switch in high position grounds terminal 1, but terminal 3 remains open. Armature current flows directly to ground through terminal 1, shunt field current flows to ground through a resistor connected between terminals 1 and 3, and the motor runs at high speed due to the weakened shunt field.
When wiper switch is turned off, and wipers are not in park position, terminal 1 is grounded through the closed motor park switch contacts. Terminals 1 and 3 are connected through the wiper switch, and the motor runs at low speed. When wipers reach their lowest point of travel, a cam on the motor output shaft opens the park switch, and the motor stops.



Pulse Wiper Operation
On models with pulse wipers, a pulse control module provides a delay wipe mode through the low speed circuit. When wiper control is in delay position, battery voltage is supplied to a capacitor in the module through a variable resistor. When the capacitor is fully charged, it activates a switching circuit which provides a ground to begin wiper operation. As the motor operates, park switch contacts close, the capacitor discharges, and the motor ground is maintained through the park switch. When wipers complete their cycle, the park switch opens and the capacitor begins to recharge. Delay between wipe cycles is determined by a variable resistor, which controls charging current to the capacitor. Higher resistance produces a longer delay.

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Some good cleaned up wiring diagrams below:

1987 R/V depicted