DESCRIPTION
The multiplex wiper system consists of a round wiper motor, washer pump, special delay circuit board (in wiper housing), and a dash mounted switch. System can be identified by a single Black/Pink wire leading to the timing circuit. The system allows the driver to adjust the interval between wiper sweeps up to a maximum of 12 seconds. For information about the Round Wiper Motor, Refer to the WIPER/WASHER SYSTEM - FRONT ROUND WIPER MOTOR article in this section.
DASHBOARD SWITCH
The switch contains a variable resistor and several sets of switch contacts. The body of the switch must be grounded.
CONSTANT SPEED OPERATION
During constant speed operation, both the pulse and park relays are closed and grounded through the control switch. Speed is controlled by varying resistance between the shunt field and ground. In "LOW", the shunt field is grounded directly at the control switch. In "MED" speed a 20 ohm resistor in the park relay and a 13 ohm resistor in the switch are connected in parallel to ground. In "HIGH", the 20 ohm resistor in the park relay connects the shunt field to ground.
PARK OPERATION
When the switch is moved to the "OFF" position, the park relay coil is opened which releases the spring-loaded relay latch arm. The pulse relay is connected to ground, and the shunt field is grounded to continue low speed operation. The continuing rotation of the motor causes the gear drive pawl to engage the relay latch arm. The output shaft and wiper arm are driven by cam action past their normal cycling point and move to the park position. The relay switch contacts are opened, and the motor stops.
DELAY OPERATION
During delay operation, the parking relay coil ground circuit is maintained at control switch which keeps it energized. This maintains 12 volt circuit to pulse relay coil. The pulse relay coil ground circuit, however, is opened at control switch and timing circuit of delay mode controls ground circuit.
WASHER OPERATION
The washer can be actuated with the wipers stopped, in a constant speed mode, or in delay. When the wipers are stopped and the washer switch is depressed, the motor starts and runs in "LOW" while the washer pump provides fluid for cleaning the windshield. When the wipers are operating in a constant speed mode, the washer will also operate with the wipers at that speed. If the washer is actuated when the wipers are in the delay mode, the circuitry is bypassed and the motor will operate in "LOW". The delay operation will resume after the wash cycle is complete.
WIPER INOPERATIVE
- With ignition "ON" and wipers off, connect test lamp between ground and terminal 2 of motor. (Scheme 5) If no power, check fuse, feed wire between fuse block and motor, or wire to terminals 2 and 5 of motor. If power present at terminal 2, touch test lamp to terminal 1.
- If wipers run, check for open between terminal 1 and switch, or for defective switch. If wipers do not run, place switch in "LOW" and connect test lamp to terminal 6 and ground. If wipers run, check for open between terminal 6 and switch, or for defective switch.
- If wipers do not run, remove washer pump cover and reattach wiring to wiper. Place switch in "LOW" and connect test lamp to Red wire terminal at pulse relay. If no power, check terminal connections, open in Red wire, or replace park relay.
- If lamp lights, connect test lamp to Orange wire terminal at pulse relay. If wiper runs, replace timing circuit board. If wiper does not run, connect test lamp to Pink/Black wire terminal at pulse relay. If no power, replace pulse relay. If lamp lights, repair internal problem in motor.
WIPER WON'T SHUT OFF
- If wipers work correctly in "DELAY", turn ignition "ON" and wiper switch "OFF". Disconnect terminal 1, 2, and 3 connector. (Scheme 5) Connect test lamp between wires to terminals 1 and 2. If power is present, terminal 1 wire is grounded or switch is defective. If no power, check park relay spring. If ok, replace park relay.
- If wipers do not stop in "DELAY" mode check to see if wipers park when ignition is turned "OFF". If so, clean wiper holding switch contacts or replace timer/switch assembly. If not, check override switch contacts, grounded Blue wire, or replace timer/switch assembly.
Multiplex Wiper Motor Test Connections. Scheme 5
BLADES CYCLE IN AND OUT OF PARK OR ONLY HIGH SPEED OPERATES
- If wiper has both speeds operational, replace park relay. If only the "HIGH" speed works, check connections at terminal 3. If ok, connect a jumper from terminal 3 to ground (with regular wiring connected).
- If wiper operates correctly, repair terminal 3 wire between motor and dash switch, or check dash switch. If wiper still does not operate, remove motor and check for intermittent open in shunt field.
ONLY LOW SPEED OPERATES
Turn ignition "ON" and wipers to "HIGH". Disconnect terminal connector. Connect test lamp between terminal 2 and 3 wires in connector. If no power, repair wiper motor. If power is present, repair terminal 3 wire or dash switch.
WIPER DELAY INOPERATIVE
If wiper is completely inoperative in "DELAY" position, place switch in "DELAY", adjust to middle of delay position, and disconnect terminal 6 wiring. Connect an ohmmeter between terminal 6 wire and ground. Resistance should be measured on 1 megohm scale. If so, replace timer/switch assembly. If not, replace dash switch.
DELAY OPERATES CONTINUOUSLY
- With ignition "ON," operate wipers in all speeds. If wipers have high speed only, or will not shut off, see previous tests. If wipers operate properly, but do not delay between wipes, place switch in mid-delay position.
- Turn wipers on and disconnect lead from terminal 6. If wipers stop, check for grounded circuit between terminal 6 and switch. If okay, replace switch.
- If wipers continue to run, remove washer pump cover and reconnect wiring. With wipers running continuously in "DELAY," disconnect lead from timing circuit to pulse relay. If wipers stop, replace timing circuit. If not, replace pulse relay.
Testing Multiplex Wiper Pulse Relay Connections. Scheme 6
REMOVAL & INSTALLATION
Note. Removal and installation procedures for wiper motor and dash switch are the same as the Round Wiper Motor. Refer to the WIPER/WASHER SYSTEM - FRONT ROUND WIPER MOTOR article in this section.