System Description

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The 1-2 shift valve performs shifting to 1st gear and other gears.

Fig 1: Identifying 1-2 Shift Valve

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DTC DETECTION CONDITION CHART

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) and (b), or (a) and (c) When the ECM directs the gearshift to switch to 2nd gear, the actual gear is shifted to 1st. When the ECM directs the gearshift to switch to 4th gear, the actual gear is shifted to 3rd. When the ECM directs the gearshift to switch to 5th gear, the engine overruns (clutch slips).	Shift solenoid valve SLT remains open or closed Valve body is blocked up or stuck (1-2 shift valve) Automatic transmission (clutch, brake or gear, etc.)

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)

and (b), or (a) and (c)

When the ECM directs the gearshift to switch to 2nd gear, the actual gear is shifted to 1st.
When the ECM directs the gearshift to switch to 4th gear, the actual gear is shifted to 3rd.
When the ECM directs the gearshift to switch to 5th gear, the engine overruns (clutch slips).

Shift solenoid valve SLT remains open or closed
Valve body is blocked up or stuck (1-2 shift valve)
Automatic transmission (clutch, brake or gear, etc.)

HINT:

Gear positions in the event of a solenoid valve mechanical problem:

ECM COMMAND GEARSHIFT CHART

ECM command gearshift

1st

2nd

3rd

4th

5th

6th

Actual gear position under malfunction

1st

3rd

⁽¹⁾

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 DURING FAIL-SAFE OPERATION

Gear position under normal conditions

1st

2nd

3rd

4th

5th

6th

Actual gear position under fail safe mode

(⁽¹⁾)

1st (⁽¹⁾)

3rd

⁽¹⁾	Under engine braking, downshifting to 1st or 2nd gear is prohibited.