The starter relay switches a very high current into the starter motor - I don't know motor cars but logic says it will be mounted directly onto the starter motor itself - it will have a big fat cable running to it (and a little control wire from the ignition switch) capable of carrying anything from 80 to 200 Amps. Just follow the fat cable from the battery - the first place it reaches will be the starter relay.
Peccavi, March 2010
