System Description
WARNING: This page is about a different car, the 2010 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. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0781 | 1-2 shift valve malfunction: Shifting to 2nd and 4th gears is impossible. When the ECM directs the gearshift to switch to 5th or 6the 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 switch to 2nd gear, the actual gear is shifted to 1st. (b) When the ECM directs the gearshift to switch to 4th gear, the actual gear is shifted to 3rd. (c) When the ECM directs the gearshift to switch to 5th gear, the engine overruns (clutch slips). |
|
HINT:
- Gear positions in the event of a solenoid valve mechanical problem:
ECM command gearshift 1st 2nd 3rd 4th 5th 6th Actual gear position under malfunction ↑ 1st ↑ 3rd N* 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 | ↑ (*1) | 1st (*1) | ↑ | 3rd | 3rd | 3rd |
*1: Under engine braking, downshifting to 1st or 2nd gear is prohibited.