First do this:
This condition may be caused by a bent park tab on the windshield wiper motor bracket.CorrectionTo correct this condition, replace the wiper motor bracket. It will be necessary to transfer the following parts listed below to the new bracket. • Wiper transmission• Wiper motor crank arm• Wiper motor
Parts InformationPart Number12368639DescriptionBracket
If this does not work, replace your wiper module. There were many problems with these in the past and is most likely the problem here. The module sits on top of the wiper motor and takes about 5 minutes to replace.