A/T - No Shift 3-4 Shift, O/D Off, Light Does Not Work
TECHNICAL BULLETIN # 316DATE 1995
TRANSMISSION: 30-80LE
SUBJECT: No 3-4 shift, O/D off light does not work
APPLICATION: ISUZU
30-80LE
No 3-4 Shift, O/D Off Light Does Not Work
A no 3-4 shift condition may exist when the O/D off lamp burns out or is missing. Figure one shows a typical circuit of the O/D cancel circuit.
When the O/D off switch is open, voltage from the O/D off indicator lamp will signal the
TCU at pin eight. This will allow a shift to fourth gear. When the switch is closed, no voltage is sent to pin eight. The TCU will not allow a shift to fourth gear under this condition. If the O/D indicator lamp is faulty or missing, the signal to enable overdrive will not occur.