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Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Multifunction Switch Circuit Test

  1. Ignition OFF, disconnect the X3 harness connector at the turn signal multifunction switch.
  2. Ignition OFF, test for less than 20 ohms between the low reference circuit terminal M and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  3. Verify the scan tool Windshield Wiper Switch parameter is Off.
    • If not the specified value, test the signal circuit terminal N for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool Wiper High Speed Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal K for a short to ground. If the circuit tests normal, replace the BCM.
  5. Install a 3-amp fused jumper wire between the signal circuit terminal N and ground. Verify the scan tool Windshield Wiper Switch parameter is Switch Fault.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Install a 3-amp fused jumper wire between the signal circuit terminal K and ground. Verify the scan tool Wiper High Speed Switch parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, replace the turn signal multifunction switch.

Wipers Do Not Park Circuit Test

  1. Ignition OFF, disconnect the harness connector at the windshield wiper motor.
  2. Ignition ON, verify the scan tool BCM Wiper Park Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
  3. Install a 3-amp fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Wiper Park Switch parameter is Active.
    • If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the windshield wiper motor.

Wiper Control Relay Control Circuit Test

  1. Ignition OFF, disconnect the X5 harness connector at the BCM.
  2. Ignition ON, verify that the low speed wipers are not on.
    • If the low speed wipers are on, test the relay control circuit terminal 20 for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
  3. Install a 10A fused jumper wire between B+ and the relay control circuit terminal 20. Verify the low speed wipers are on.
    • If the low speed wipers are not on, test the relay control circuit for an open/high resistance or short to ground. If the circuit tests normal replace the underhood fuse block.
  4. If all circuits test normal, replace the BCM.

Wiper Speed Relay Control Circuit Test

  1. Ignition OFF, disconnect the X5 harness connector at the BCM.
  2. Install a 10A fused jumper wire between B+ and the WIPER CONTROL relay control circuit terminal 20.
  3. Ignition ON, verify that the high speed wipers are not on.
    • If the high speed wipers are on, test the WIPER SPEED relay control circuit terminal 21 for a short to ground. If the circuit tests normal, replace the underhood fuse block.
  4. Install a 10A fused jumper wire between the WIPER SPEED relay control circuit terminal 21 and ground. Verify the high speed wipers are on.
    • If the high speed wipers are not on, test the relay control circuit for an open/high resistance or short to voltage. If the circuit tests normal replace the underhood fuse block.
  5. If all circuits test normal, replace the BCM.

Wiper Motor Circuit Test

  1. Disconnect the harness connector at the windshield wiper motor.
  2. Test for less that 1 ohm between the wiper motor ground circuit terminal 5 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the low speed motor control circuit terminal 1 and ground.
  4. Ignition ON, command the Wiper Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
    • 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 underhood fuse block.
  5. Connect a test lamp between the high speed motor control circuit terminal 4 and ground.
  6. Wiper switch in the LOW position, command the Wiper High Speed Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
    • 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 underhood fuse block.
  7. If all circuits test normal, replace the windshield wiper motor.
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