BMW models X-5 of the E-53 series are equipped with a horn consisting of high and low tone sources, which are installed behind the front bumper. To protect the horn from overload, it is switched on through the contacts of the relay, which is activated by the horn panel located on the steering wheel. Checking the sound signal must be carried out in the following order. Connect the audio signal using auxiliary wires directly to the battery. In this case, connect the violet-blue wire to «+» AB, and brown wire with «–» AB and make sure the signal sounds.
When installing a sound signal, tighten the bolts of its fastening with a torque of 10 Nm (1.0 kgf·m).