When conditions (a) and (b), or (a) and (c) are met. (2-trip detection logic)
| Last Modified: 11-29-2007 | 1.6 C | |
| Service Category: Drivetrain | Section: Automatic Transmission/Transaxle | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM000000XP103IX |
| Title: AB60E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia) | ||
|
DTC |
P0781 |
1-2 Shift (1-2 Shift Valve) |
DESCRIPTION
The 1-2 shift valve performs shifting to 1st gear and other gears. When shifting to 2nd and 4th gears is impossible, or when the ECM directs the gearshift to switch to 5th and 6th gear and the engine overruns (clutch slips), this DTC is output.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P0781 |
(a) When the ECM directs the transmission to switch to 2nd gear, the actual gear is shifted to 1st. (b) When the ECM directs the transmission to switch to 4th gear, the actual gear is shifted to 3rd. (c) When the ECM directs the transmission 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
1st
3rd
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 |
1st* |
1st* |
3rd |
3rd |
3rd |
3rd |
HINT:
1st*: Under engine braking, downshifting to 1st or 2nd gear is prohibited.
MONITOR DESCRIPTION
This DTC indicates that the 1-2 shift valve in the valve body is locked in the direction the spring compresses.
The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF" and switching oil pressure to the valves in the valve body.
The ECM calculates the "actual" transmission gear by comparing the signals from the input speed sensor (NT) and the output speed sensor (SP2). The ECM can detect many mechanical problems in the shift solenoids, valve body, transmission clutches, brakes, and gears. If the ECM detects that the actual gear position and the commanded gear position are different, it will illuminate the MIL and store the DTC .
MONITOR STRATEGY
|
Related DTCs |
P0781: Valve body/Rationality check |
|
Required sensors/Components |
Valve body, Automatic transmission assembly |
|
Frequency of operation |
Continuous |
|
Duration |
Condition (A) and (B) 0.4 seconds Condition (C) 3 seconds Condition (D) 1 second |
|
MIL operation |
2 driving cycles |
|
Sequence of operation |
None |
TYPICAL ENABLING CONDITIONS
All
|
The monitor will run whenever the following DTCs are not present |
P0500: VSS P0748 - P0799: Trans solenoid (range) |
|
Turbine speed sensor circuit |
Not circuit malfunction |
|
Output speed sensor circuit |
Not circuit malfunction |
|
Shift solenoid valve S1 circuit |
Not circuit malfunction |
|
Shift solenoid valve S2 circuit |
Not circuit malfunction |
|
Shift solenoid valve S3 circuit |
Not circuit malfunction |
|
Shift solenoid valve S4 circuit |
Not circuit malfunction |
|
Shift solenoid valve SR circuit |
Not circuit malfunction |
|
Shift solenoid valve SL1 circuit |
Not circuit malfunction |
|
Shift solenoid valve SL2 circuit |
Not circuit malfunction |
|
ECT (Engine coolant temperature) sensor circuit |
Not circuit malfunction |
|
KCS sensor circuit |
Not circuit malfunction |
|
ETCS (Electric Throttle Control System) |
Not system down |
|
Transmission position |
"D" |
|
Duration time from shifting "N" to "D" |
4 seconds or more |
|
ECT |
40°C (104°F) or more |
|
Spark advance from max. retard timing by KCS control |
0° crankshaft angle or more |
|
Engine |
Starting |
Condition (A)
|
ECM selected gear |
2nd |
|
Vehicle speed |
2 km/h (1.3 mph) or more |
|
Output speed |
2nd → 1st down-shift point or more |
|
Throttle valve opening angle |
9% or more at 2000 rpm (Conditions vary with engine speed) |
Condition (B)
|
ECM selected gear |
4th |
|
Vehicle speed |
2 km/h (1.3 mph) or more |
|
Throttle valve opening angle |
9% or more at 2000 rpm (Conditions vary with engine speed) |
Condition (C)
|
Current ECM selected gear |
5th |
|
Last ECM selected gear |
4th |
|
Vehicle speed (During transition from 4th to 5th gear) |
Less than 100 km/h (62.1 mph) |
Condition (D)
|
ECM selected gear |
5th |
|
Engine speed -Turbine speed (NE - NT) (After transition to 5th gear) |
150 rpm or less |
|
Vehicle speed (After transition to 5th gear) |
Less than 100 km/h (62.1 mph) |
TYPICAL MALFUNCTION THRESHOLDS
Both of the following conditions are met: Condition (A), and Condition (B), (C) or (D)
Condition (A)
|
Turbine speed/Output speed (NT/NO) |
3.11 or more, and 7.58 or less (This means actual gear is 1st) |
Condition (B)
|
Turbine speed/Output speed (NT/NO) |
1.24 or more, and 1.49 or less (This means actual gear is 3rd) |
Condition (C)
|
Turbine speed - Output speed x 4th gear ratio (NT - NO x 4th gear ratio) |
1000 rpm or more |
Condition (D)
|
Turbine speed - Output speed x 5th gear ratio (NT - NO x 5th gear ratio) |
1000 rpm or more |
INSPECTION PROCEDURE
PROCEDURE
|
1. |
CHECK DTC OUTPUT (IN ADDITION TO DTC P0781) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read the DTCs using the Techstream.
Result
|
Result |
Proceed to |
|---|---|
|
Only P0781 is output |
A |
|
P0781 and other DTCs are output |
B |
HINT:
If any other codes besides P0781 are output, perform troubleshooting for those DTCs first.
|
|
2. |
PERFORM ACTIVE TEST USING TECHSTREAM (RUNNING TEST) |
HINT:
Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.
(a) Warm up the engine.
(b) Turn the ignition switch off.
(c) Connect the Techstream to the DLC3.
(d) Turn the ignition switch to ON.
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.
(g) According to the display on the Techstream, perform the Active Test.
HINT:
While driving, the shift position can be forcibly changed with the Techstream.
Engine and ECT
|
Tester Display |
Test Part |
Control Range |
Diagnostic Note |
|---|---|---|---|
|
Control the Shift Position |
Operate shift solenoid valve and set each shift position by yourself |
|
Possible to check operation of shift solenoid valves [Vehicle Condition] 50 km/h (30 mph) or less |
HINT:
- This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.
- The 4th to 5th and 5th to 6th up-shift must be performed with the accelerator pedal released.
- The 6th to 5th and 5th to 4th down-shift must be performed with the accelerator pedal released.
- Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
- The shift position commanded by the ECM is shown in the Data List display on the Techstream.
-
Gear positions in the event of a solenoid valve mechanical problem:
Tester command gearshift
1st
2nd
3rd
4th
5th
6th
Actual gear position under malfunction
1st
1st
3rd
3rd
N*
N*
N*: Neutral
OK:
Gear position changes in accordance with the Techstream command.
|
|
3. |
PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT) |
NOTICE:
- Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
- Be careful to prevent SST hose from interfering with the exhaust pipe.
- Perform the test with the A/C OFF.
HINT:
Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.
|
(a) Remove the test plug on the transmission case center right side and connect SST. |
SST: 09992-00095
09992-00231
09992-00271
(b) Connect the Techstream to the DLC3.
(c) Start the engine and warm it up.
(d) Measure the line pressure with SST.
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.
(g) According to the display on the Techstream, perform the Active Test.
(h) Measure the line pressure.
Engine and ECT
|
Tester Display |
Test Part |
Control Range |
Diagnostic Note |
|---|---|---|---|
|
Activate the Solenoid (SLT)* |
Operate the shift solenoid SLT and raise line pressure |
ON or OFF HINT:
|
[Vehicle Condition]
|
HINT:
*: Activate the Solenoid (SLT) in the Active Test is performed to check the line pressure changes by connecting SST to the automatic transmission, which is used in the Hydraulic Test
as well. Please note that the pressure values in the Active Test and Hydraulic Test are different.
OK:
The line pressure changes as specified when performing the Active Test.
|
|
4. |
CLEAR DTC AND PERFORM RUNNING TEST |
(a) Clear the DTC
.
(b) Check the DTC again after conducting the Monitor Drive Pattern
.
OK:
No DTC code output.
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