Diagnosis And Testing - Wiper And Washer System: Notes
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. Refer to CLEANING and 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.
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.
| WIPER AND WASHER SYSTEM DIAGNOSIS | ||
|---|---|---|
| CONDITION | POSSIBLE CAUSES | CORRECTION |
| WIPER MOTOR DOES NOT OPERATE IN ANY SWITCH POSITION | 1. Ineffective motor ground circuit. | 1. Test and repair open wiper motor ground circuit if required. |
| 2. Ineffective motor feed circuits. | 2. Test and repair low speed and high speed feed circuits between the Power Distribution Center (PDC) and wiper motor if required. | |
| 3. Ineffective wiper on/off relay control circuit. | 3. Test and repair wiper on/off relay control circuit between the BCM and the PDC if required. | |
| 4. Ineffective SCM inputs or outputs. | 4. Use a diagnostic scan tool and the appropriate diagnostic information for further SCM diagnosis. | |
| 5. Ineffective SAS inputs or outputs. | 5. Use a diagnostic scan tool and the appropriate diagnostic information for further SAS diagnosis. | |
| 6. Ineffective BCM inputs or outputs. | 6. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information. | |
| 7. Ineffective wiper on/off relay. | 7. Test and replace open or shorted wiper on/off relay (PDC unit) if required. | |
| 8. Ineffective wiper motor. | 8. Test and replace open or shorted wiper motor if required. | |
| WIPERS DO NOT PARK CORRECTLY | 1. Ineffective wiper motor park switch input circuit. | 1. Test and repair wiper park switch input circuit between BCM and wiper motor if required. |
| 2. Ineffective BCM inputs or outputs. | 2. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information. | |
| 3. Ineffective wiper motor park switch. | 3. Test and replace wiper motor if required. | |
| WIPER MOTOR OPERATES SLOWLY IN ALL SWITCH POSITIONS | 1. Ineffective wiper motor. | 1. Check amperage draw with linkage disconnected from wiper motor output shaft. Correct draw should be about 6 amperes. If incorrect, refer to the appropriate Possible Cause that follows: |
| 2. Amperage draw too low. | 2. Test and repair shorted low and high speed feed circuits if required. | |
| 3. Amperage draw too high. | 3. With linkage disconnected from wiper motor output shaft, check linkage and pivots for binding. If binding is detected, repair or replace wiper linkage module if required. If no linkage binding detected, replace the wiper motor if required. | |
| WIPERS RUN AT HIGH SPEED WITH SWITCH LOW SPEED SELECTED OR AT LOW SPEED WITH SWITCH HIGH SPEED SELECTED | 1. Ineffective motor feed circuit wiring. | 1. Test and repair low speed and high speed feed circuits between the PDC and the wiper motor if required. |
| 2. Ineffective wiper high/low relay control circuit. | 2. Test and repair wiper high/low relay control circuit between the BCM and the PDC if required. | |
| 3. Ineffective wiper high/low relay. | 3. Test and replace open or shorted wiper high/low relay (PDC unit) if required. | |
| WASHER PUMP DOES NOT OPERATE | 1. Ineffective washer pump ground circuit. | 1. Test and repair open washer pump ground circuit if required. |
| 2. Ineffective washer pump feed circuits. | 2. Test and repair washer pump feed circuits between BCM and washer pump if required. | |
| 3. Ineffective SCM inputs or outputs. | 3. Use a diagnostic scan tool and the appropriate diagnostic information for further SCM diagnosis. | |
| 4. Ineffective SAS inputs or outputs. | 4. Use a diagnostic scan tool and the appropriate diagnostic information for further SAS diagnosis. | |
| 5. Ineffective BCM inputs or outputs. | 5. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information. | |
| 6. Ineffective washer pump. | 6. Test and replace open or shorted washer pump if required. | |