Division 2.2.2.18.1

It is permitted to connect the braking system to a power supply in addition to that available from the ISO 7638:2003 connector above. However, when an additional power supply is available the following provisions shall apply:

1. 2.2.2.18.1.1.

   in all cases the ISO 7638:2003 power supply is the primary power source for the braking system, irrespective of any additional power supply that is connected. The additional supply is intended to provide a backup should a failure of the ISO 7638:2003 power supply occur;

2. 2.2.2.18.1.2.

   it shall not have an adverse effect on the operation of the braking system under normal and failed modes;

3. 2.2.2.18.1.3.

   in the event of a failure of the ISO 7638:2003 power supply the energy consumed by the braking system shall not result in the maximum available power from the additional supply being exceeded;

4. 2.2.2.18.1.4.

   the towed vehicle shall not have any marking or label to indicate that the towed vehicle is equipped with an additional power supply;

5. 2.2.2.18.1.5.

   a failure warning device is not permitted on the towed vehicle for the purposes of providing a warning in the event of a failure within the towed vehicle braking system when the braking system is powered from the additional supply;

6. 2.2.2.18.1.6.

   when an additional power supply is available it shall be possible to verify the operation of the braking system from this power source;

7. 2.2.2.18.1.7.

   should a failure exist within the electrical supply of energy from the ISO 7638:2003 connector the requirements of points 4.2.3 of Annex XII and 4.1 of Annex XI with respect to failure warning shall apply irrespective of the operation of the braking system from the additional power supply.