Shift Indicator - A/T: Description and Operation
With the 
starter switch in 
ON or 
START battery voltage is applied to the automatic transmission mode switch and the A/T shift indicator control unit from 
BACK UP/TURN LIGHT fuse CB-15. The automatic transmission mode switch sends a signal to the A/T shift indicator control unit corresponding to the gear selected. The A/T shift indicator control unit applies voltage to the appropriate A/T shift indicator causing it to light up.