D4 - Check Interval Select Input Signal

^ Rotate interval control on the wiper switch from "S" to "F".

^ Measure resistance between circuits 590 (DB/W) and 993 (BR/W).

^ Is resistance 3.3k-103.3k ohms?

YES -- Replace wiper control module,

NO -- Go to D5. D5 - Check Interval Select Input Signal at Wiper Switch