ABS failure warning light

ABS failure warning light

On vehicles equipped with ABS and an EBD device, there is a special ABS failure warning light.

The new type of warning light, known as "INTELLIGENT", comprises an LED (D2) controlled by an electronic circuit which, as illustrated in the diagram at the side, allows the warning light to come on both if there is an actual failure in the ABS system and if the connection between pin 16 of the control unit (1) and the instrument panel (2) is interrupted or short circuited to earth.

• D1: Protective diode
• D2: LED
• R1 and R2: Load resistances

EBD function failure signal

A failure in the EBD function is signalled simultaneously by the braking system failure warning light (1) in the dashboard and the ABS system failure warning light (2) both coming on.

The warning light (1) in the dashboard coming on without the ABS warning light (2) coming on means that there is not an EBD malfunction, but that there is a different fault (low brake fluid level, handbrake applied).

Conversely, the ABS warning light only coming on without the warning light (1) coming on, indicates a failure in the ABS system as described in the relevant chapter of this manual without the operation of the EBD device being adversely affected.

If there is a failure in the EBD function, the distribution of the brake force between the front and rear axles starts to fail with the consequent risk of the rear wheels locking during braking.