The Underhood Electrical Center (UEC) controls the washer motor based on an input from the windshield washer switch which is part of the Steering Wheel Module (SWM). The UEC monitors the washer switch over the LSCAN data line. Both circuits at the washer pump are normally grounded at the UEC. When the front washers are commanded on the UEC applies B+ to circuit  228 and Circuit  392 remains grounded to activate a front windshield wash cycle. When a rear window wash cycle is requested the UEC applies B+ to Circuit  392 and ground to circuit  228 to command rear washers on.

Schematic Reference

Wiper/Washer Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Wiper/Washer System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, wiper switch in the OFF position, observe the scan tool Rear Window Washer Status parameter while cycling the WASH switch ON and OFF. The parameter should cycle between OFF and ON.

⇒	If the parameter does not cycle between the specified values, replace the wiper washer switch.

2. Operate the rear washers using the washer switch. Verify the washer pump activates and the low speed wipers turn on.

⇒	If the washer pump does not activate, refer to Washer Pump Circuit Malfunction.

⇒	If the low speed wipers do not turn on, refer to Windshield Wiper System Malfunction .

Washer Pump Circuit Malfunction

1. Ignition OFF, disconnect the Underhood Electrical Center (UEC)
2. At connector X 1 connect a jumper wire between terminal  43 and ground.
3. At connector X 1 connect a fused jumper wire between terminal  42 and B+.
4. Verify the washer pump activates.

⇒	If the rear washer pump does activate replace the UEC. refer to Control Module References for UEC replacement.

5. If the rear washer fluid pump does not activate, test the control circuit for an open/high resistance. If the fuse opens, test the control circuit for a short to ground.
6. If the washer pump still does not operate test for less then 3 ohms between terminal  42 and terminal  1 at washer pump connector.

⇒	If greater than the specified ranges, test the ground circuit for an open/high resistance. If all values are with in specification and washer are inoperative refer to washer pump component testing.

Washer Pump

1. Ignition OFF, disconnect the harness connector at the washer pump.
2. Install a 10A fused jumper wire between the control terminal 1 and 12 volts. Install a jumper wire between the ground terminal 2 and ground.
3. Verify the washer pump is activated.

⇒	If the washer pump does not activate , replace the washer pump.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.