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Home >> Buick >> 2015 >> Regal GS, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Wiper/Washer Systems >> Wiper System And Washer System >> Diagnostic Information and Procedures >> DTC B3715 or B3875: Windshield Wiper Relay >> Circuit/System Testing

Circuit/System Testing

DTC B3715

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR12B Windshield Wiper Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10Ω between the ground circuit terminal 85 and ground.
    • If 10Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2Ω in the ground circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, repair the open/high resistance in the ground connection.
    • If less than 10Ω 
  3. Ignition ON. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
  4. Verify the test lamp turns ON and OFF when commanding the Windshield Wiper Motor Relay On and Off with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, and disconnect the X4 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2Ω in the control circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, and disconnect the X4 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1V between the control circuit 16 X4 and ground.
      • If 1V or greater, repair the short to voltage on the circuit.
      • If less than 1V, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  5. Test or replace the KR12B Windshield Wiper Relay.

DTC B3875

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR12C Windshield Wiper Speed Control Relay.
  2. Verify a test lamp Illuminates between the B+ circuit terminal 85 and ground.
    • If the test lamp does not illuminate 

      Replace the X50A Fuse Block - Underhood.

    • If the test lamp illuminates 
  3. Ignition ON. Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
  4. Verify the test lamp turns ON and OFF when commanding the Windshield Wiper Motor Relay High and Stop with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1V between the control circuit terminal 24 X5 and ground.
      • If 1V or greater, repair the short to voltage on the circuit.
      • If less than 1V
    3. Ignition OFF.
    4. Test for less than 2Ω in the control circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the X5 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit terminal 24 X5 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  5. Test or replace the KR12C Windshield Wiper Speed Control Relay.
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