D5 - Check Interval Select Input Signal at Wiper Switch
^ Disconnect harness from wiper switch.
^ Rotate interval control on the wiper switch from "S" to "F".
^ Measure resistance between terminals of wiper switch for circuits 590 (DB/W) and 993 (BR/W).
^ Is resistance 3.3k-1O3.3k ohms?
YES -- Check for open wires between the wiper switch and the wiper control module. Service as required.
NO -- Check for damaged wiper switch. Service as required.