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Rear 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

Rear Wiper Switch Signal

2

1

1

--

Rear Window Wiper Control

1

1

2

--

Rear Window Wiper Relay Control

B370B 02, 1

1

2

--

Rear Window Wiper Ground

--

1

1

--

1. Washer Inoperative.

2. Washer Always ON.

Circuit/System Description

The body control module (BCM) controls the single speed rear wiper motor by its active high output to the external rear wiper motor relay. When the BCM activates its output and applies battery to the coil of the relay, the relay energizes, allowing battery voltage from the fuse to be applied through the switched contacts of the rear wiper motor relay to the control input of the rear wiper motor. The motor then operates continuously at low speed.

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

Verify the Rear Wiper Command parameter is active when operating the rear wipers.

⇒If the parameter is not active, refer to the Rear Wiper/Washer Switch Circuit Malfunction.
⇒If the parameter is active, refer to the Rear Wiper Motor Circuit Malfunction.

Circuit/System Testing

Rear Wiper/Washer Switch Circuit Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the S82 windshield wiper/washer switch.
  2. Test for less than 5 Ω between the low reference terminal 2 and ground.
    3. ⇒If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  3. Test for greater than 10 V between the signal circuit terminal 4 and ground.
    4. ⇒If less than the specified value, test the signal circuit for an open/high resistance.
  4. If all circuits test normal, replace the S82 windshield wiper/washer switch.

Rear Wiper Motor Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the M45 rear wiper motor.
  2. Test for less than 5 Ω between the ground circuit terminal C and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal B and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for an open/high resistance and a short to ground. If all circuits test normal, replace the X50A underbonnet fuse block.
  4. Install a test lamp between the control circuit terminal A and the ground circuit terminal C.
  5. Using the S82 windshield wiper/washer switch, command the rear wiper ON and OFF. The test lamp should turn ON and OFF as commanded. Observe this in the switch position continuous and intermittent.
    6. ⇒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, test or replace the K9 BCM.
  6. If all circuits test normal, test or replace the M45 rear wiper motor.

Component Testing

Output Control Test

Ignition ON, command the Rear Wiper Relay On and OFF with the rear wiper switch. Observe the KR7 rear wiper relay clicks and the M45 rear wiper motor runs.

⇒If the KR7 rear wiper relay does not work, replace the X50A underhood fuse block.
⇒If the KR7 rear wiper relay does work, but the M45 rear wiper motor does not run, test the M45 rear wiper motor ground and control circuit.
⇒If all circuits test normal, replace the M45 rear wiper motor.

Relay Test

  1. Ignition OFF, connect the harness connector X2 at the X50A underhood fuse block.
  2. Disconnect the harness connector X4 at the K9 BCM.
  3. Test for 60-200 Ω between terminal 10 X4 and ground.
    4. ⇒If the resistance is not within the specified range, test the control circuit for a short to ground or an open/high resistance. If all circuits test normal, test or replace the X50A underhood fuse block.

Dynamic Test

  1. Ignition OFF, disconnect the harness connector at the M45 rear wiper motor.
  2. Install a 25 A fused jumper wire between the control terminal A and B+. Install a jumper wire between the ground terminal C and ground.
  3. Verify the M45 rear wiper motor is operating.
    4. ⇒If the M45 rear wiper motor is not operating, replace the M45 rear wiper motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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


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