Wiper On Vehicle (Multiplex System): Notes

When troubleshooting wiper switch and harness, remove harness from terminal No. 3 at motor. See Figure. Use 12-volt test lamp to probe center terminal of switch harness. With test lamp grounded and ignition switch on, test lamp should light.
To check other terminals in connector, attach alligator clip end of test light to a 12-volt source. Probe 2 outside harness terminals. Move wiper switch to low-speed position. Tester should light when contact is made at either of outside terminals. Move switch to high position. Tester should light at one outside terminal only. With switch in off position, light should light at opposite outside terminal only.
If switch and harness are okay, check relay switch by providing 12-volt source to washer motor. Ensure that motor is well grounded. Connect a 12-volt source to Black/Pink wire. If motor runs under these conditions and not when wiper switch is used, trouble is in relay switch.
If motor does not run when 12-volt source is provided, trouble is in motor. Make preliminary check of following items; Body wiring connected to relay switch, terminal board and wiper switch. Wiper motor to dash mounting screws are tight and corrosion free. Ensure fuse is not blown. With ignition switch on, there is a 12-volt supply at center terminal of relay switch and terminal board.