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Circuit/System Testing

WARNING: This page is about a different car, the 2015 GMC Terrain and 2015 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.

Windshield Wiper/Washer Switch Circuit Test

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S78 turn signal/multifunction switch. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the low reference circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify the scan tool Windshield Wiper Switch parameter is Off.
    • If not Off 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the signal circuit terminal 3 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 Off 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 2.
  6. Verify the scan tool Windshield Wiper Switch parameter is On.
    • If not On 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If On 
  7. Verify the scan tool Windshield Wiper High Speed Switch parameter is Inactive.
    • If not Inactive 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the signal circuit 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 Inactive 
  8. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
  9. Verify the scan tool Windshield Wiper High Speed Switch parameter is Active.
    • If not Active 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If Active 
  10. Test or replace the S78 turn signal/multifunction switch.

Windshield Wiper Motor Circuit Test

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M75 Windshield Wiper Motor. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal C and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Connect a test lamp between the control circuit terminal E and the ground circuit terminal C.
  5. Verify the test lamp turns ON and OFF when commanding the LOW speed wipers ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the 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 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the KR12C windshield wiper speed control relay.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test replace the KR12C windshield wiper speed control relay.
    • If the test lamp turns ON and OFF 
  6. Connect a test lamp between the B+ circuit terminal D and the control circuit terminal C.
  7. Verify the test lamp turns ON and OFF when commanding the HIGH speed wipers ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF.
    4. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the KR12B windshield wiper relay.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the 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, test or replace the KR12B windshield wiper relay.
    • If the test lamp turns ON and OFF 
  8. Test or replace the M75 windshield wiper motor.

Wiper Park Circuit Test

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M75 windshield wiper motor. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal C and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ωor greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify the scan tool Windshield Wiper Park Switch parameter is Inactive.
    • If Active 
    1. Ignition OFF, disconnect the X4 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the signal circuit 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 Inactive 
  5. Install a 3 A fused jumper wire between the signal circuit terminal B and the ground circuit terminal C.
  6. Verify the scan tool Windshield Wiper Park Switch parameter is Active.
    • If Inactive 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If Active 
  7. Test or replace the M75 windshield wiper motor.

Windshield Wiper Dual Relays Test

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR12B Windshield Wiper Relay and the KR12C Windshield Wiper Speed Control Relay. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuits listed below and ground.
    • Terminal 87A at the KR12B Windshield Wiper Relay
    • Terminal 86 at the KR12C Windshield Wiper Speed Control Relay
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuits end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuits listed below and ground.
    • Terminal 87 at the KR12B Windshield Wiper Relay
    • Terminal 85 at the KR12C Windshield Wiper Speed Control Relay
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the B+ circuits end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the B+ circuits and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for infinite resistance between the B+ circuits and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the X50A underhood fuse block.
    • If the test lamp illuminates 
  5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85 at the KR12B Windshield Wiper Relay.
  6. Verify the test lamp turns ON and OFF when commanding the Windshield Wipers ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, 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 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X4 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  7. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86 at the KR12C Windshield Wiper Speed Control Relay.
  8. Verify the test lamp turns ON and OFF when commanding the Windshield Wipers ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If greater than 1 V, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
    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, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  9. Ignition OFF, reconnect the KR12C Windshield Wiper Speed Control Relay and KR12B Windshield Wiper Relay.
  10. Disconnect the X4 Harness connector at the K9 Body Control Module, ignition ON.
  11. Connect a 3 A fused jumper wire between B+ and the control circuit terminal 16 at the KR12B Windshield Wiper Relay.
  12. Verify the M75 Windshield Wiper Motor is activated.
    • If the M75 Windshield Wiper Motor does not activate 
    1. Ignition OFF, disconnect the KR12C Windshield Wiper Speed Control Relay and KR12B Windshield Wiper Relay.
    2. Test for less than 2 Ω in the control circuit between control circuit terminal 30 at the KR12C Windshield Wiper Speed Control Relay and the control circuit terminal 30 at the KR12B Windshield Wiper Relay.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω
    3. Reconnect the KR12B Windshield Wiper Relay and the X4 harness connector at the K9 Body Control Module.
    4. Connect a test lamp between the control circuit terminal 30 and the control circuit terminal 87 at the KR12C Windshield Wiper Speed Control Relay, ignition ON.
    5. Verify the test lamp illuminates when commanding the Windshield Wipers ON.
      • If test lamp does not illuminate, test or replace the KR12C Windshield Wiper Speed Control Relay.
      • If test lamp illuminates, KR12B Windshield Wiper Relay.
    • If the M75 Windshield Wiper Motor does activate 
  13. All OK.
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