[ANNEX X U.K. Test requirements for vehicles with anti-lock braking systems
4. GENERAL REQUIREMENTS U.K.
4.1. Any electrical failure or sensor anomaly that affects the system with respect to the functional and performance requirements in this Annex, including those in the supply of electricity, the external wiring to the controller(s), the controller(s) () and the modulator(s) shall be signalled to the driver by a specific optical warning signal. U.K.
4.1.1. The warning signal shall light up when the anti-lock braking system is energised and, with the vehicle stationary, it shall be verified that none of the above-mentioned defects are present before extinguishing the signal. U.K.
4.1.2. The static sensor check may verify that a sensor was not functioning the last time that the vehicle was at a speed greater than 10 km/h () . Also during this verification phase, the electrically controlled pneumatic modulator valve(s) shall cycle at least once. U.K.
4.2. Motor vehicles equipped with an anti-lock braking system and authorised to tow a trailer equipped with such a system, with the exception of vehicles of categories M 1 and N 1 , shall be fitted with a separate optical warning signal for the anti-lock braking system of the trailer, meeting the requirements of point 4.1 of this Annex. U.K.
4.2.1. This warning signal shall not light up when a trailer without an anti-lock braking system is coupled or when no trailer is coupled. This function shall be automatic. U.K.
4.3. The abovementioned optical warning signal(s) shall be visible even in daylight and it shall be easy for the driver to check that they are in working order. U.K.
4.4. Except for vehicles of categories M 1 and N 1 , O 1 and O 2 , the electrical connections used for the anti-lock braking systems of towing vehicles and trailers shall be effected by a special connector conforming to ISO Standard 7638-1985 or ISO/DIS Standard 7638-1996 () . U.K.
4.5. In the event of a failure of the anti-lock braking system, the residual braking performance shall be that prescribed for the vehicle in question in the event of a failure of a part of the transmission of the service braking system (see point 2.2.1.4 of Annex I). This requirement shall not be construed as a departure from the requirements concerning secondary braking. In the case of trailers, the residual braking performance in the event of a defect in the anti-lock braking system according to point 4.1 of this Annex shall be at least 80 % of the laden prescribed performance for the service braking system of the relevant trailer. U.K.
4.6. The operation of the system shall not be adversely affected by magnetic or electrical fields () . U.K.
4.7. A manual device may not be provided to disconnect or change the control mode () of the anti-lock braking system, except on off-road motor vehicles of categories N 2 or N 3 . Where a device is fitted to N 2 or N 3 off-road motor vehicles, the following conditions shall be met: U.K.
4.7.1. the motor vehicle with the anti-lock braking system disconnected or the control mode changed by the device referred to in point 4.7 above shall satisfy all the relevant requirements in the Appendix to point 1.1.4.2 of Annex II; U.K.
4.7.2. an optical warning signal shall inform the driver that the anti-lock braking system has been disconnected or the control mode changed; the anti-lock failure warning signal may be used for this purpose; U.K.
4.7.3. the anti-lock braking system shall automatically be reconnected/returned to on-road mode when the ignition (start) device is again set to the ‘ on ’ (run) position; U.K.
4.7.4. the vehicle user's handbook provided by the manufacturer should warn the driver of the consequences of manual disconnection or mode change of the anti-lock braking system; U.K.
4.7.5. the device referred to in point 4.7 above may, in conjunction with the towing vehicle, disconnect/change the control mode of the anti-lock braking system of the trailer; a separate device for the trailer alone is not permitted.] U.K.