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Windscreen Wiper System Malfunction

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Windscreen Wiper High Speed Relay B+

1, 2

1, 2

--

--

Windscreen Wiper Switch Low Signal

1

1

1

--

Windscreen Wiper Switch High Signal

4

2

2

--

Windscreen Wiper Motor Park Switch Signal

3

3

--

--

Front Wiper Relay Control

B3715 02

B3715 04

B3715 01

--

Windscreen Wiper High Speed Relay Control

B3875 02

B3875 04

B3875 01

--

Windscreen Wiper High Speed Relay Control

2

2

4

--

Front Wiper Motor Low Speed Control

1

1

4

--

Windscreen Wiper Switch Low Reference

--

1, 2

1, 2

--

Windscreen Wiper Motor Ground

--

1, 2, 3

--

--

Front Wiper Relay Ground

--

1

--

--

1. Delay or Low Speed Wipers Inoperative

2. High Speed Wipers Inoperative

3. Wipers Do Not Park

4. Wipers Always ON

Circuit/System Description

The Body Control Module (BCM) controls the wiper motor based on input from the windscreen wiper/washer switch. The BCM monitors the wiper/washer switch through two separate signal circuits and a ground circuit. The windscreen wiper switch high signal circuit is used to determine high speed wiper operation, the windscreen wiper switch low signal is used to determine low speed, intermittent, and mist operation through the use of a resistor ladder, and the windscreen washer switch signal circuit is used to determine washer operation.

The BCM controls the windscreen wiper motor through two output controls, controlling two relays which determine the desired wiper speed, high or low.

Reference Information

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

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, windscreen wiper/washer switch in the OFF position, verify the scan tool Windscreen Washer Switch parameter is Inactive.
    2. ⇒If not the specified value, refer to Washer Malfunction .
  2. Wiper switch in the OFF position, verify the scan tool Windscreen Wiper Switch parameter is Off.
    3. ⇒If not the specified value, refer to the Windscreen Wiper/Washer Switch Circuit Test.
  3. Wiper switch in the OFF position, verify the scan tool Windscreen Wiper High Speed Switch parameter is Inactive.
    4. ⇒If not the specified value, refer to the Windscreen Wiper/Washer Switch Circuit Test.
  4. Wiper switch in the LO position, verify the scan tool Windscreen Wiper Switch parameter is Low.
    5. ⇒If not the specified value, refer to the Windscreen Wiper/Washer Switch Circuit Test.
  5. Wiper switch in the HIGH position, verify the scan tool Windscreen Wiper High Speed Switch parameter is Active.
    6. ⇒If not the specified value, refer to the Windscreen Wiper/Washer Switch Circuit Test.
  6. Wiper switch in the INT position, observe the scan tool Windscreen Wiper Switch parameter while cycling the delay adjustment switch from long delay to short delay. The parameter should cycle between D1 and D5 as each delay position is selected.
    7. ⇒If not the specified value, test or replace the windscreen wiper/washer switch.
  7. Wiper switch in the LO position, verify the windscreen wipers are cycling at the low speed.
    8. ⇒If the wipers are not operating at low speed, refer to the Windscreen Wiper Motor Circuit Test.
  8. Wiper switch in the HIGH position, verify the windscreen wipers are cycling at high speed.
    9. ⇒If the wipers are not operating at high speed, refer to the Windscreen Wiper Motor Circuit Test.
  9. Observe the scan tool BCM Wiper Park Switch parameter. The reading should display Active when the wipers are parked and Inactive with the wipers ON or out of the park position.
    10. ⇒If the Wiper Park Switch parameter is always Active or Inactive or the wipers do not park, refer to the Wiper Park Circuit Test.

Circuit/System Testing

Windscreen Wiper/Washer Switch Circuit Test

  1. Ignition OFF, disconnect the harness connector at the S82 windscreen wiper/washer switch.
  2. Verify a test lamp illuminates between low reference circuit terminal 2 and B+.
    3. ⇒If the test lamp does not illuminate, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  3. Ignition ON, test for greater than 10 V between the signal circuit terminal 1 and ground.
    4. ⇒If less than the specified value, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Test for greater than 10 V between the signal circuit terminal 3 and ground.
    5. ⇒If less than the specified value, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the S82 windscreen wiper/washer switch.

Windscreen Wiper Motor Circuit Test

  1. Ignition OFF, disconnect KR12B windscreen wiper relay.
  2. Test for less than 5 Ω between the ground circuit terminal 85 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Test for less than 5 Ω between the ground circuit terminal 87A and ground.
    4. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 87 and ground.
    5. ⇒If the test lamp does not illuminate, test or replace the X50A underbonnet fuse block.
  5. Install a test lamp between the control circuit terminal 86 and ground.
  6. Command the LOW speed wipers ON and OFF using the S82 windscreen wiper/washer switch. The test lamp should turn ON and OFF as commanded.
    7. ⇒If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  7. Ignition OFF, disconnect the KR12C windscreen wiper speed control relay.
  8. Test for less than 5 Ω between the control circuit terminal 30 of the KR12B windscreen wiper relay and the control circuit terminal 30 of the KR12C windscreen wiper speed control relay.
    9. ⇒If greater than the specified range, replace the X50A underbonnet fuse block.
  9. Connect the KR12B windscreen wiper relay.
  10. Test for less than 5 Ω between the control circuit terminal 30 of the KR12C windscreen wiper speed control relay and ground.
    11. ⇒If greater than the specified range, test or replace the KR12B windscreen wiper relay.
  11. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 85 from the KR12C windscreen wiper speed control relay and ground.
    12. ⇒If the test lamp does not illuminate, test or replace the X50A underbonnet fuse block.
  12. Install a test lamp between the control circuit terminal 30 of the KR12C windscreen wiper speed control relay and ground.
  13. Command the LOW speed wipers ON using the S82 windscreen wiper/washer switch. The test lamp should illuminate when commanding the LOW speed wipers ON.
    14. ⇒If the test lamp does not illuminate, replace the KR12B windscreen wiper relay.
  14. Install a test lamp between control circuit terminal 86 of the KR12C windscreen wiper speed control relay and B+.
  15. Command the HIGH speed wipers ON and OFF using the S82 windscreen wiper/washer switch. The test lamp should turn ON and OFF as commanded.
    16. ⇒If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  16. Ignition OFF, connect the KR12C windscreen wiper speed control relay. Disconnect the harness connector X1 at the M75 windscreen wiper motor.
  17. Test for less than 5 Ω between the ground circuit terminal C and ground.
    18. ⇒If greater than the specified value, test the ground circuit for an open/high resistance.
  18. Connect a test lamp between the control circuit terminal B and ground.
  19. Ignition ON, command the LOW speed wipers ON and OFF using the S82 windscreen wiper/washer switch. The test lamp should turn ON and OFF when changing between the commanded states.
    20. ⇒If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, test or replace the KR12C windscreen wiper speed control relay.
    ⇒If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the KR12C windscreen wiper speed control relay.
  20. Connect a test lamp between the control circuit terminal D and ground.
  21. Command the HIGH speed wipers ON and OFF using the S82 windscreen wiper/washer switch. The test lamp should turn ON and OFF when changing between the commanded states.
    22. ⇒If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, test or replace the KR12C windscreen wiper speed control relay.
    ⇒If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the KR12C windscreen wiper speed control relay.
  22. If all circuits test normal, test or replace the M75 windscreen wiper motor.

Wiper Park Circuit Test

  1. Ignition OFF, disconnect the wiring harness plug at the windscreen wiper motor.
  2. Ignition ON, test for greater than 10 V between signal circuit terminal A and ground.
    3. ⇒If less than the specified value, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, test or replace the K9 BCM.
  3. If the circuit tests normal, test or replace the M75 windscreen wiper motor.

Component Testing

Windscreen Wiper Motor

  1. Ignition OFF, disconnect the harness connector X1 at the M75 windscreen wiper motor.
  2. Install a 25 A fused jumper wire between the control terminal B and 12 V. Install a jumper wire between the ground terminal C and ground.
  3. Verify the M75 windscreen wiper motor is operating in the low speed mode.
    4. ⇒If the M75 windscreen wiper motor is not in the low speed mode, replace the M75 windscreen wiper motor.
  4. Install a 25 A fused jumper wire between the control terminal D and 12 V. Install a jumper wire between the ground terminal C and ground.
  5. Verify the M75 windscreen wiper motor is operating in the high speed mode.
    6. ⇒If the M75 windscreen wiper motor is not in the high speed mode, replace the M75 windscreen wiper motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Windscreen Wiper Motor Replacement
    •  Relay Replacement : Within an Electrical Center → Attached to Wire Harness
    •  Windscreen Wiper and Washer Switch Replacement
    • Control Module References for BCM replacement, programming and setup
   


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