Wiper In Vehicle (Multiplex System): Notes

To troubleshoot wiper switch and harness, remove harness from terminal 3 at motor. 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 lamp to a "B+" source (hot wire) and probe 2 outside harness terminals. Move wiper switch to low-speed position. Test lamp should light when contact is made at either of the outside terminals. Move switch to high position. Test lamp 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 hot wiring the washer motor. Make sure that motor is well grounded and run a hot wire to Black with Pink stripe wire. If motor runs under these conditions and not when wiper switch is used, the trouble is in the relay switch. If motor does not run when hot wired, then the trouble is in the motor.

Make preliminary check of the following items:

• Body wiring connected to relay switch and terminal board and wiper switch.
• Wiper motor to dash mounting screws are tight and corrosion free.
• Fuse.
• With ignition switch on, there is a 12-volt supply at center terminal of relay switch and terminal board.