System Description
WARNING: This page is about a different car, the 2015 Lexus IS 250 and 2014 Lexus IS 250. However, it is still accessible from the selected car via links, so may be relevant.
The 1-2 shift valve performs shifting to 1st gear and other gears.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
|---|---|---|---|---|---|
| P0781 | 1-2 Shift (1-2 Shift Valve) | 1-2 shift valve malfunction: Shifting to 2nd and 4th gears is impossible. When the ECM directs the gearshift to change to 5th or 6th gear, the engine overruns (clutch slips). (2-trip detection logic) (a) and (b), or (a) and (c) (a) When the ECM directs the gearshift to change to 2nd gear, the actual gear is shifted to 1st. (b) When the ECM directs the gearshift to change to 4th gear, the actual gear is shifted to 3rd. (c) When the ECM directs the gearshift to change to 5th gear, the engine overruns (clutch slips). |
|
Comes on | DTC stored |
HINT:
- Gear positions in the event of a solenoid valve mechanical problem:
ECM commanded gear 1st 2nd 3rd 4th 5th 6th Actual gear position under malfunction 1st 1st 3rd 3rd N* N* *: Neutral
- Gear position during fail-safe operation:
If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.
Gear position under normal conditions 1st 2nd 3rd 4th 5th 6th Actual gear position under fail safe mode 1st (*1) 1st (*1) 3rd 3rd 3rd 3rd *1: Under engine braking, downshifting to 1st or 2nd gear is prohibited.