Circuit/System Testing
WARNING: This page is about a different car, the 2011 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
Horn Switch Circuit Test
- Ignition OFF, disconnect the harness connector at the horn switch.
- Test for less than 1 Ω between the ground circuit terminal 2 and ground.
- If greater than the specified range, test the ground circuit for and open/high resistance.
- Connect the harness connector at the horn switch. Disconnect the X2 harness connector at the underhood fuse block.
- Connect a test lamp between B+ and the control circuit terminal K4.
- 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.
- Connect the X2 harness connector at the underhood fuse block. Disconnect the harness connector at the horn assembly.
- 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.
- If all circuits test normal, replace the underhood fuse block.
Horn Circuit Test
- Ignition OFF, disconnect the harness connector at the horn assembly.
- Test for less than 1 Ω between the ground circuit terminal A and ground.
- If greater than the specified range, test the ground circuit for and open/high resistance.
- Connect a test lamp between the control circuit terminal B and ground.
- 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 HORN fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the underhood fuse block.
- If the test lamp is always OFF and the HORN fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the horn assembly.
- If all circuit test normal, test or replace the horn assembly.
Horn - Poor Tone
- Ignition OFF, disconnect the harness connector at the horn assembly.
- Test for less than 1 Ω between the horn assembly ground circuit terminal A and ground.
- If greater than the specified range, test the ground circuit for a high resistance.
- Disconnect the X1 harness connector at the underhood fuse block.
- Test for less than 1 Ω between the control circuit terminal D2 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.
- If all circuits test normal, test or replace the horn assembly.