Symptom: The horn does not sound or sound after various failed attempts, even with a hard pressure on the steering wheel, when the car is On. But if I turn off the car and slight press the steering wheel the horn sounds OK.

Can someone point me how to troubleshoot this? I think it could be a “short” or maybe a “relay” because it seems to work when the ignition is off. But once I turn the car On, sometimes work, sometimes not…