Wiper and Washer Systems: Testing and Inspection

DIAGNOSIS AND TESTING - WIPER AND WASHER SYSTEM

WARNING:
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to take the proper precautions could result in accidental airbag deployment.

If the wiper motor operates, but the wipers do not move on the windshield, replace the ineffective wiper motor or wiper linkage module. If the washer pump/motor operates, but no washer fluid is dispensed on the glass; or, if the wipers operate, but chatter, lift or do not clear the glass, clean and inspect the wiper and washer system components as required. Wipers And Washers - Cleaning and Wipers And Washers - Inspection.

The hard wired wiper and washer system circuits and components may be diagnosed and tested using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the wiper and washer system or the electronic controls and communication between other modules and devices that provide some features of the wiper and washer system. The most reliable, efficient and accurate means to diagnose the wiper and washer system or the electronic controls and communication related to wiper and washer system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

NOTE:
The wiper and washer switches are integral to the multi-function switch. The multi-function switch communicates with the Steering Control Module (SCM), which is also integral and internal to the multi-function switch. The SCM communicates with the Steering Angle Sensor (SAS) which is integral to the clockspring over the Local Interface Network (LIN) data bus. The SAS communicates with the Body Control Module (BCM) (also known as the Common Body Controller/CBC) over the Controller Area Network (CAN) data bus. Before performing any of the following tests, determine whether the other functions of the multi-function switch are operational. If other functions of the multi-function switch are ineffective, diagnose and repair that problem before attempting to repair the Wiper and Washer System.









FALSE WIPES (AUTOMATIC WIPER ONLY)

False wipes are unnecessary wipes that occur when the control knob of the multi-function switch is in one of the five automatic wiper sensitivity positions and no rain or moisture is apparent within the wipe pattern on the windshield glass. Because this system is designed to operate whenever it detects moisture, if the switch is in one of the automatic wiper sensitivity positions any road spray, bug splatters, or mist from passing cars or trucks may occasionally cause the wipers to cycle. These are normal characteristics of this system and are not false wipes.

False wipes generally are the result of foreign material or flaws that interfere with the system optics. The optics for this system allow the Light Rain Sensor Module (LRSM) (also known as the Light Sensor Module/LSM, the Rain Sensor Module/RSM or the Rain Light Sensor/RLS) to precisely transmit several Infrared (IR) light beams and precisely monitor the intensity of these beams reflected from the outer surface of the windshield glass to determine the presence of moisture. The sensitivity of this system is such that anything that distorts the focus or intensity of the IR light beams or affects the ability of the photo diodes within the LRSM to see and accurately measure these light beams can result in the LRSM logic misinterpreting the resulting input data as moisture on the windshield. The optics for this system include the lenses of the LRSM, the lens of the LRSM bracket, the adhesive pad layer that bonds the LRSM bracket to the inside of the windshield and the windshield glass.

The following procedure should only be used if false wipe occurrences are frequent and persistent. Perform diagnosis of the wiper system, the multi-function switch, the Steering Control Module (SCM), the Steering Angle Sensor (SAS) and the LRSM using a diagnostic scan tool and the appropriate diagnostic procedures before performing the following:

NOTE:
The Light Rain Sensor Module (LRSM) mounting bracket is serviced as a unit with the windshield glass. If either the bracket or the glass is ineffective or damaged, the entire LRSM bracket and windshield glass unit must be replaced.

1. Carefully inspect the outer surface of the windshield glass for physical damage, including scratches, cracks or chips in the vicinity of the LRSM mounting bracket lenses. Scratches, cracks or chips in the windshield glass outside the area of the LRSM mounting bracket lenses will not cause false wipes. If OK, go to Step 2. If not OK, replace the damaged windshield.

2. From the outside of the windshield glass, carefully inspect the adhesive layer between the windshield glass and the LRSM bracket for any large voids. If an adhesive void greater than about 1 millimeter (0.04 inch) is observed, replace the flawed LRSM mounting bracket and windshield unit. If OK, go to Step 3.

3. Lightly pull the LRSM away from the windshield bracket to confirm that both sides of the spring steel LRSM mounting band are fully engaged with the mounting bracket on the inside of the windshield glass. If OK, go to Step 4. If not OK, reinstall the LRSM onto the bracket as required.

4. Remove the LRSM from the mounting bracket. Inspect the LRSM lenses and the mounting bracket lens for contamination. If OK, go to Step 5. If not OK, clean any foreign material from each of these lenses using rubbing alcohol and a lint-free cloth.

5. Carefully inspect the LRSM for any physical damage, including scratches on the LRSM lenses. If OK, go to Step 6. If not OK, replace the damaged LRSM.

6. Carefully inspect the LRSM mounting bracket for any physical damage, including scratches on the LRSM bracket lens. If not OK, replace the damaged LRSM bracket and windshield as a unit.