Ford Mustang (1999-2004) Service Manual: Principles of Operation

Multifunction Wipers

The front wiper/washer feature controls the speed of the front windshield wipers and the amount of washer fluid sprayed on the front windshield when requested by the customer. There are five (5) wiper modes: OFF, LOW, HIGH, INTERVAL, and WASH.

Wiper Motor Speeds HIGH and LOW

There are two wiper speeds, HIGH and LOW. When the GEM detects the ignition switch circuits are in the RUN or ACC states, and the GEM detects a high or low speed request from the wiper mode circuits, the GEM will activate the wiper ON and OFF and the wiper speed circuits accordingly.

Wiper Motor Speeds Interval

There are one to seven wiper speed intervals, ranging from 1.5 seconds to 20 seconds in delay time respectively, which can be selected. When the GEM detects the ignition switch circuits are in the RUN or ACC states, and the GEM detects an interval selection of 1 through 7 from the delay/wash circuits, the GEM will activate the wiper ON and OFF and the wiper speed circuits accordingly.

Washers

When the GEM detects the ignition switch circuits are in RUN or ACC states, and the GEM detects a WASH request from the wiper delay/wash circuits, the GEM will activate the washer pump relay circuit for as long as the request is present up to 10 seconds.

Activation of the washer pump when in INTERVAL or OFF is delayed until a wash request is active for a minimum amount of time. In this scenario, the wash request must be present continuously for at least 210 ms. This allows a wash request that is present for less than 210 ms, to provide additional functionality by initiating a single wipe, called "mist wipe". The mist wipe function is a single wipe at low speed without activating the washer motor.

When in LOW or HIGH, any WASH request, regardless of the length of time it is present, will activate the washer pump. When in INTERVAL or OFF mode, upon deactivation of the washer motor, this feature shall provide two wipes at low speed before returning to the INTERVAL or OFF state as defined by the inputs. These additional wipes are provided to clear residual washer fluid from the front windshield.