If its a 3 terminal (BAT FLD GEN/ARM) or a 4 terminal (BAT LOAD FLD GEN/ARM) THERE SHOULD BE NOOOOOOOOOOOOO WIRE TO THE LIGHT SWITCH !!!!!!!
On many 4 terminal VR's BAT LOAD FLD are side by side while GEN/ARM is underneath or off on one side all by itself
If its a 2 wire (BAT GEN/ARM) Cutout Relay then the gennys FLD does wire to the light switch.
SOUNDS LIKE IT MAY NOT BE WIRED RIGHT !!!!!!!!
It may be polarized at neg ground at the shop but now youre at Pos ground so be sure to polarize BEFORE STARTING
Im headed to the Colorado mountains so may not have net for a while. Look at the diagrams and what I said in both my posts