by DonaldNZ » Mon Jan 14, 2019 10:29 pm
The relay winding is driven by the alternator once it starts to charge,
if the relay is removed the alternator will still charge [if its the same as supplied diagram]
three small terminals on alternator
S = Sense 12+ live all the time, W/B white with blue trace although usually wiring diagrams white blue is written as W/L to avoid confusion with black. In Geeves diagram S is connected to battery via 50A fuse so the alternator knows how much to charge / regulator external battery reference]
IG = Ignition 12+ when key on, B/Y Black with Yellow trace, in diagram its connected to 15A Engine fuse along with normally open contact on charge relay. its purpose to the alternator is to turn off and on the regulator in the alternator.
L= Light outputs battery +, this when alternator has reached cut in speed and is charging, WG which is either white with green trace or might be grey trace. Its purpose is to extinguish charge [battery] warning light, change relay contact state to advise alternator charging, drive belt is ok & extinguish bulb test functions of other dash warning bulbs. some systems also use this to trigger a start inhibit when alternator running.
For testing of the alternator
confirm battery + to large B+ alternator terminal stud [I use one of a set of jumper leads for testing and battery to S & IG terminal and a 12v test light [with a 5w or less bulb] one end of bulb to battery + the other to the L terminal at alternator. The bulb will be on until alternator reaches cut in speed [say ~ >1200 alternator rpm]
Alternator L terminal is a good place to hook up + terminal [via a 1A fuse to protect the $150 regulator] of an engine run hour meter if required as it will only clock [add] time once engine started.