[aussie merc]

ok this is there for radio static etc the gauges used where not a constant power flow design and used a bimetallic strip in the senders to control current [make and break] this can cause static to pulse through the radio [if fitted] also found at the oil sender and have seen them at the temp sender where electric temp gauges are used [ie 39/40] they also prolong gauge life as they reduce the contacts in the strips burning [just like ignition points and condenser]