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Circuit/System Testing

Horn Switch Circuit Test

  1. Ignition OFF, disconnect the X4 harness connector at the underhood fuse block.
  2. Connect a test lamp between the control circuit terminal G1 and B+.
  3. Ignition ON, press and release the horn switch. 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 ground or a sticking horn switch. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage, an open high resistance, or a horn switch which is not closing.
  4. Ignition OFF, connect the harness connector at the underhood fuse block. Disconnect the harness connector at the appropriate horn.
  5. Verify that a test lamp does not illuminate between the control circuit terminal B and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
  6. If all circuits test normal, replace the underhood fuse block.

Horn Circuit Test

  1. Ignition OFF, disconnect the harness connector at the appropriate horn.
  2. Test for less than 1 ohm between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for and open/high resistance.
  3. Connect a test lamp between the control circuit terminal B and ground.
  4. Press and release the horn switch. 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 and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
    • If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the horn.
  5. If all circuits test normal, test or replace the horn.

Horn - Poor Tone

  1. Ignition OFF, disconnect the harness connector at the appropriate horn.
  2. Test for less than 1 ohm between the horn ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for a high resistance.
  3. Disconnect the X1 harness connector at the underhood fuse block.
  4. Test for less than 1 ohm between the control circuit terminal E5 at the underhood fuse block and the control circuit terminal B at the horn assembly.
    • If greater than the specified range, test the control circuit for a high resistance.
  5. If all circuits test normal, test or replace the horn.
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