Ford 2003 Mustang Workshop Manual page 3886

To test the wiper motor, disconnect the windshield wiper mounting arm and pivot shaft from the
windshield wiper motor; refer to Pivot Arm .
Disconnect the wiper motor. Connect the (1) green lead from (2) (ARBST) to the battery negative (-)
post. Connect the (3) red lead from ARBST to the wiper motor (4) common brush terminal (terminal 3).
Test the low speed mode by connecting a (5) cable from the battery positive (+) post to the (6) low
speed brush terminal (terminal 4) and measure the current draw. If the current draw is greater than 3.5
amperes, install a new windshield wiper motor.
Test the high speed mode by connecting a cable from the battery positive (+) post to the (7) high
speed brush terminal (terminal 5) and measure the current draw. If the current draw is greater than 5.5
amperes, install a new wiper motor.