5.2.2.17.

Trailers equipped with an electric control line and O3 and O4 category trailers equipped with an anti-lock system, shall be fitted with either one or both of the following, for the electric control transmission:
(a)    A special electrical connector for the braking system and/or anti-lock system, conforming to ISO 7638:2003;[15], [16]
(b)    An automated connector meeting the requirements specified in Annex 22.
Failure warning signals required from the trailer by this Regulation shall be activated via the above connectors. The requirement to be applied to trailers with respect to the transmission of failure warning signals shall be those, as appropriate, which are prescribed for motor vehicles in paragraphs 5.2.1.29.4., 5.2.1.29.5. and 5.2.1.29.6. of this Regulation.

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5.2.2.17. Trailers equipped with an electric control line and O3 and O4 category trailers equipped with an anti-lock system, shall be fitted with a special electrical connector for the braking system and/or anti-lock system, conforming to ISO 7638:2003.15, [5] Failure warning signals required from the trailer by this Regulation shall be activated via the above connector. The requirement to be applied to trailers with respect to the transmission of failure warning signals shall be those, as appropriate, which are prescribed for motor vehicles in paragraphs 5.2.1.29.4., 5.2.1.29.5. and 5.2.1.29.6. a0c0