GM Service Manual Online
For 1990-2009 cars only

Wiper/Washer System Components

The Wiper/Washer System consists of the following components:

    • Windshield wiper/washer switch
    •  Underhood Electrical Center (UEC)
    •  Steering Wheel Module (SWM)
    •  Rear Electrical Center (REC)
    • WPR Relay K 5
    • WPR HI Relay K 6
    • Windshield wiper motor
    • Windshield washer fluid pump
    • Windshield washer fluid level switch
    • Rain sensor module
    •  Fuse F 14 30 A
    •  Fuse F 15 30 A

Refer to Master Electrical Component List .

Power and Grounds

The underhood electrical center (UEC) is a central module in the front of the car placed close to the battery, It consists of a fuse box, a relay box and a control module which communicates on LS CAN. The UEC controls all the functions of the front and rear wipers. The UEC gets power directly from the battery. There are two internal relays that are controled by the module portion of the UEC based off the messages it recieves from the wiper switch in the steering wheel module (SWM). When activated the wiper stalk does not stay in a detented position but returns to a neutral position . The system is turned off by pushing the switch in the other direction.

Modes of Operation

The normal wiper system function positions are as follows:

    • Tip
    • Intermittent
    • LOW
    • HIGH
    • Wiper blade service position, With the ignition OFF but key in "O" position

Wiper Speeds

All the wiper speeds are controled by LS CAN messaging from the SWM to the UEC. The UEC activates the wiper relays to obtain the desired wiper speed.

Moisture Sensitive Wipers

The rain sensor is connected to the UEC by a UART data line. With moisture sensitive wipers if intermittent wipers are selected the UEC decides the wiper speed depending on the amount of rain measured by the rain sensor. If the rain sensor fails the systems operates like an ordinary delay system without moisture sensitive wipers.

Front Washer Operation

If the SWM requests to activate the front washers a LS CAN message is sent to the UEC, the UEC then activates the washer pump and the wipers. If the vehicle is moving below a certain speed the wipers are activated a bit later than the washers. The amount of wiper movements depends on how long the wiper switch is held in the wash position.

Front washers

The front windshield washers are controlled by the SWM sending a LS CAN message to the UEC . The UEC then activates the front washer pump and the wipers. The amount of wash and wiper movement depend on how long the washer switch has been held on.