Air horns, system operation - GF54.35-P-0001PP

MODELS 203 

Requirements for operation: 

• Circuit 15R ON

  When the contact for the air horn activation (S110s5) or (S111s5) is closed by pressure on the multifunction steering wheel's (MFL) center pad, the air horns (H2) are activated in the following operational sequence:

• The EZS control unit (N73) registers the signals from the airhorn contact (S110s5) or airhorn contact (S111s5) in voltage-coded form.
• The EZS control unit (N73) responds by transmitting a corresponding message to the front SAM control unit with fuse and relay module (N10/1) via the Class B Controller Area Network (interior).
• The front SAM control unit with fuse and relay module (N10/1) then activates the airhorn relay (N10/1kl).
• The airhorn relay (N10/1kl) switches to relay power for the airhorns (H2) through its own Terminal 30.
• The horn sounds.

Because one of the airhorn (H2) wires is always grounded, supplying power through Terminal 30 on the airhorn relay (N10/1kl) activates the horns. The coil in the airhorn relay (N10/1kl) is permanently connected to Terminal 15R. When the airhorns (H2) are activated, the front SAM control unit with fuse and relay module (N10/1) grounds the other end.

The 2 airhorn contacts (S110s5) and the 2 airhorn contacts (S111s5) are on a PCB located beneath the MFL multifunction steering wheel's center pad. This system incorporates 4 contacts to ensure that the airhorns (H2) can be activated through pressure applied to any point on the center pad. The two airhorn contacts on the right side (S110s5) and the two contacts on the left side (S111s5) are arranged in parallel. Together with the buttons in the switch cluster on the left side of the multifunction steering wheel (S110) and the right-side cluster on the multifunction steering wheel (S111) the signals are registered by the EZS control unit (N73) as voltage-coded data. When another element within the switch cluster on the left (S110) or right (S111) of the multifunction steering wheel is activated simultaneously with the airhorn contact (S110s5) or (S111s5), the airhorn has priority.

Diagnosis 

Diagnosis is carried out with STAR DIAGNOSIS.