Mike wrote:
Sorry to ressurect such an old topic - but looking at my connection and the advice given by "Convertible Mini" doesn't seem to make sense. The fact that the 'S' terminal is voltage sensing and doesn't draw any current when the engine is off does make sense BUT how would the "ALT" light function work if the "S" terminal is connected "straight to the battery" as suggested? I mean the "alt" light connects to the L terminal and that turns to +12V when there's a +12v to the 'S' terminal. It switches off when the alternator starts charging (ie the engine is spinning it). Now if there's a constant +12v to the S terminal, the 'Alt' light will be always on too whenever the engine is off regardless of whether ignition is on and drain the battery wouldn't it?
The lamp gets its 12 volts from the ignition switch (when it's in the 'on' position only). The alternator grounds the lamp via a current detecting reed switch. If there is no current being produced by the alternator, then the light will remain grounded and hence switched on.
