It makes for three, rather than two, beam distributions. To accomplish this, the third relay's control circuit must be complete only when the high beam headlamps are aactivated and when your newly added dashboard switch is turned on. This circuit will change the operating mode of your high beam headlamps. Do not use high beam headlamps in traffic. It is dangerous and obnoxious to use your lamps in a manner that creates glare for other drivers.
Some cars have dashboard-mounted indicators to tell the driver when a headlamp has burned out.
The function of such devices can be disrupted by the installation of headlamp relays. There are ways to maintain the function of a bulb-outage indicator while still using relays. No part of this text may be reproduced in any form without express permission of author. Permission to quote is granted for the purposes of communication with the author.