i think u mean 'RELAY'.. 85 (is switch '+' teminal),86( is switch '-' or ground), 87(is your consumer's '+' teminal.... cosumer like horn or blub)...and 30(is the direct battery supply.. u might wanna put a fuse for this line).... hope info like this can help... if u need to learn more go to howstuffworks.com and find out... :)