E181

Notes on Fault Tree
The fourth gear switch is a normally closed switch located in the transmission idle opens when 4th gear oil is present. The ECM provides 5 volts on CKT 446 which is grounded when the switch is closed (4th gear not present). ECM input EI80 will show "LO" when the transmission is not in 4th gear (CKT 446 grounded) and "HI" when the 4th gear switch is open (transmission in 4th gear).
When the transmission reaches 4th gear the °F status light should appear on the ECC head. If this status light is on when the transmission is not in 4th gear, CKT 446 is open and must be repaired.

Notes on Intermittents

Manipulate affected wiring while observing the °F status light. If the fault is induced, the °F status light will flash on. Repair intermittent open in CKT 446.