Front wiper and washer system operation is completely controlled by the SCM, EMIC and TIPM logic circuits, and
that logic will only allow these systems to operate when the ignition switch is in the ACCESSORY or ON positions.
The TIPM uses intelligent, high current, self-protected high side switches to control wiper system operation by ener-
gizing or de-energizing the wiper motor low and high speed brushes. The TIPM uses an H-bridge circuit to control
the operation of the reversible washer pump/motor unit. The right multi-function switch circuitry receives battery cur-
rent and a clean ground output from the SCM, then provides analog and multiplexed inputs to the SCM to indicate
the selected front wiper and front washer system mode.
To diagnose the front wiper and washer system or the electronic controls and communication related to front wiper
and washer system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic infor-
mation.
OPERATING MODES
Following are paragraphs that briefly describe the operation of each of the front wiper and washer system operating
modes.
CONTINUOUS WIPE MODE
When the LOW position of the control knob on the control stalk of the right (wiper) multi-function switch is selected
the SCM sends an electronic wiper switch low status message to the EMIC over the LIN data bus, the EMIC
relays an electronic wiper switch low request message to the TIPM over the CAN data bus, then the TIPM directs
battery current to the low speed brush of the wiper motor, causing the wipers to cycle at low speed.
When the HIGH position of the control knob is selected the SCM sends an electronic wiper switch high status
message to the EMIC, the EMIC relays an electronic wiper switch high request message to the TIPM, then the
TIPM directs battery current to the high speed brush of the wiper motor, causing the wipers to cycle at high speed.
When the OFF position of the multi-function switch control knob is selected, the SCM sends an electronic wiper
switch off status message to the EMIC, the EMIC relays an electronic wiper switch off request message to the
TIPM, then one of two events will occur. The event that occurs depends upon the position of the wiper blades on
the windshield at the moment that the control knob OFF position is selected.
If the wiper blades are in the down position on the windshield when the OFF position is selected, the park switch
that is integral to the wiper motor is closed to ground, which provides a hard wired park switch sense input to the
TIPM. The TIPM then de-energizes the wiper motor and the wiper motor ceases to operate. If the wiper blades are
not in the down position on the windshield at the moment the OFF position is selected, the park switch is an open
circuit and the TIPM continues running the wiper motor at low speed until the wiper blades are in the down position
on the windshield and the park switch input to the TIPM is again closed to ground.
INTERMITTENT WIPE MODE
When the control knob on the control stalk of the right (wiper) multi-function switch is moved to one of the five
DELAY interval positions the SCM sends an electronic wiper switch delay interval status message to the EMIC,
the EMIC relays an electronic wiper switch delay interval request message to the TIPM, then the TIPM electronic
intermittent wipe logic circuit responds by calculating the correct length of time between wiper sweeps based upon
the selected delay interval input.
The TIPM monitors the changing state of the wiper motor park switch through a hard wired park switch sense input.
This input allows the TIPM to determine the proper intervals at which to energize and de-energize the wiper motor
intermittently for one low speed cycle at a time.
The TIPM logic is also programmed to provide vehicle speed sensitivity to the selected intermittent wipe delay inter-
vals. In order to provide this feature the TIPM monitors electronic vehicle speed messages from the Controller
Antilock Brake (CAB) and doubles the selected delay interval whenever the vehicle speed is about 16 kilometers-
per-hour (10 miles-per-hour) or less.
MIST WIPE MODE
When the control stalk of the right (wiper) multi-function switch is moved downward to the momentary MIST position,
the SCM sends an electronic wiper mist mode status message to the EMIC, the EMIC relays an electronic wiper
mist mode request message to the TIPM, then the TIPM energizes the low speed brush of the wiper motor for as
long as the switch is held closed, then de-energizes the motor when the state of the switch changes to open, park-
ing the wiper blades near the base of the windshield. The TIPM can operate the front wiper motor in this mode for
PM
WIPERS/WASHERS - SERVICE INFORMATION
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