ECM Input EI81: Fourth Gear Switch: Notes

The 4th gear switch is a normally closed switch located in the transmission which is open when 4th gear oil is present. The ECM provides 5 volts on circuit No. 446 which is grounded when the switch is closed (4th gear not present). ECM input EI81 will show "LO" when the transmission is not in 4th gear (circuit No. 446 grounded) and "HI" when 4th gear switch is open (transmission in 4th gear).

When the transmission reaches 4th gear, the "°F" status light should light. If this status light is on when the transmission is not in 4th gear, circuit No. 446 is open.