Automatic Transmission - Diagnostics: Overview Toyota Sequoia I рестайлинг

SYSTEM DESCRIPTION

The ECT (Electronic controlled automatic transmission) is an automatic transmission that electronically controls shift timing using the ECM. The ECM detects electrical signals that indicate engine and driving conditions, and controls the shift point, based on driver habits and road conditions. As a result, fuel efficiency and power transmission performance are improved.

Shift shock has been reduced by controlling the engine and transmission simultaneously.

In addition, the ECT has features such as follows

1. Diagnostic function.
2. Fail-safe function when a malfunction occurs.

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1. CHECK FLUID LEVEL Using SST, create a short-circuit between terminals TC and CG of the DLC3. SST 09843-18040 Start the engine and run at idle. The A/C switch must be turned off. On models with active height control suspension & adaptive variable suspension, turn the height control switch off. Slowly move the shift lever through all positions from P to L, and move it back to the P position. Switch to the fluid temperature detection mode. Move the shift lever from the N to the D position, or from D to N, within 1.5 seconds. (Repeat this operation for 6 seconds or more.) OK: The A/T OIL TEMP warning light comes on for 2 seconds and then goes off. Return the shift lever to the P position and disconnect terminals TC and CG. Idle the engine to raise oil temperature. Lift up the vehicle immediately after the meter indicator light (ATF temperature warning light) comes on. The A/T OIL TEMP warning light indicates the ATF temperature according to the following table. AFT TEMPERATURE DESCRIPTION ATF Temp. Less than optimized temperature Optimized temperature More than optimized temperature A/T OIL TEMP warning light OFF ON Blinking Remove the overflow plug and check the fluid level. Standard: AFT LEVEL DESCRIPTION When ATF overflows ATF level is higher than specification (Go to step k) When ATF does not overflow ATF level is equal to or lower than specification (Go to step i) HINT: "Overflow" indicates the condition under which ATF drains out from the overflow tube. The capacity of the overflow tube is approximately 3 cc. If the amount of drained ATF is little, only the fluid remaining in the tube has drained out. This condition is not considered as "overflow". Remove the refill plug. Add ATF through the refill hole until it flows out from the overflow hole. Fluid type: Toyota genuine ATF WS When the draining ATF has become a trickle, install the overflow plug with a new gasket. Install the refill plug if removed. Lower the vehicle. Turn the ignition switch off to stop the engine.
2. CHECK FLUID CONDITION If the fluid smells burnt or is black, replace it (see step 6
3. INSPECT AND ADJUST SHIFT LEVER POSITION When shifting the shift lever from the N position to other positions, check that the lever can be shifted smoothly and accurately to each position and that the position indicator comes on in accordance with the shift lever position. If the indicator and shift lever position do not match, carry out the following adjustment procedures. Remove the nut and disconnect the shift control cable from the control shaft lever. Move the control shaft fully rearward. Return the control shaft lever 2 notches to the N position. Set the shift lever to the N position. Connect the shift control cable and temporarily install the control shaft lever nut. While holding the shift lever lightly toward the R position side, tighten the control shaft lever nut. Torque: 14.5 N.m (148 kgf Cm, 11 ft. lbf) Start the engine and make sure that the vehicle moves forward when shifting the lever from the N to the D position and reverses when shifting it to the R position.
4. INSPECT AND ADJUST PARK/NEUTRAL POSITION Check that the engine can be started when the shift lever is in the N or P position, but cannot be started in other positions. If operation cannot be done as stated above, carry out the following adjustment procedures. Loosen the park/neutral position switch bolt and set the shift lever to the N position. Align the groove with the neutral basic line. Hold in position and tighten the bolt. Torque:13 N.m (130 kgf° Cm, 9 ft. lbf) For continuity inspection of the park/neutral position switch, see «CIRCUIT INSPECTION»(ref-227567-S27512550062006040600000).
5. CHECK IDLE SPEED Idle speed (In N position and air conditioner OFF): 700 +/- 50 RPM
6. ADD AUTOMATIC TRANSMISSION FLUID When adding maximum amount of fluid: [*1] Lift up the vehicle while keeping it level. Remove the refill plug and overflow plug. Add ATF through the refill hole until it drains out from the overflow hole. NOTE: Be sure to add Toyota genuine ATF WS. Temporarily install the gasket and overflow plug. Torque: 20 N.m (204 kgf° Cm, 15 ft. lbf) Add the proper amount of ATF through the refill hole. NOTE: Refill amount differs depending on the related procedures indicated below. REFILL PROCEDURE Related procedures Refill amount Removal and installation of oil pan 1.7 liters (1.8 us qts, 1.5 Imp Qts) Removal of transmission valve body assy 4.3 liters (4.5 us qts, 3.8 Imp Qts) Removal of torque converter assy 5.4 liters (5.7 us qts, 4.8 Imp Qts) Temporarily install the O-ring and refill plug. Torque: 39 N.m (400 kgf° Cm, 29 ft. lbf) Lower down the vehicle. Using SST, create a short-circuit between terminals TC and CG of the DLC3. SST 09843-18040 Start the engine and run at idle. NOTE: The A/C switch must be turned off. On models with active height control suspension & adaptive variable suspension, turn the height control switch off. Slowly move the shift lever from the P to the 2-L position. Return the shift lever to the P position. Switch to the fluid temperature detection mode. Move the shift lever from the N to the D position, or from D to N, within 1.5 seconds. (Repeat this operation for 6 seconds or more.) OK: The A/T OIL TEMP warning light comes on for 2 seconds and then goes off. Disconnect terminals TC and CG after confirming the above condition. Idle the engine to raise the fluid temperature. Lift up the vehicle immediately after the meter indicator light (ATF Temperature Warning Light) comes on. NOTE: Add fluid only when the meter indicator light is on. Perform this procedure while the engine is idling. Remove the overflow plug. If ATF overflows, proceed to [*2]. If ATF does not overflow, proceed to [*3]. HINT: "Overflow" indicates the condition under which ATF drains out from the overflow tube. NOTE: Capacity of the overflow tube is approximately 3 cc. When fluid overflows: [*2] Install the overflow plug with a new gasket when the draining ATF has become a trickle. Torque: 20 N.m (204 kgf° Cm, 15 ft.lbf) Install the refill plug with a new O-ring. Torque: 39 N.m (400 kgf° Cm, 29 ft.lbf) Lower down the vehicle. Turn the ignition switch off and remove the SST. Check for fluid leaks in the transmission. If there are leaks, it is necessary to repair or replace O-rings, FIPGs, oil seals, plugs or other related parts. When fluid does not overflow: [*3] Remove the refill plug. Add ATF through the refill hole until it drains out from the overflow hole. Install the overflow plug with a new gasket when the draining ATF has becomes a trickle. Torque: 20 N.m (204 kgf° Cm, 15 ft. lbf) Install the refill plug with a new O-ring. Torque: 39 N.m (400 kgf° Cm, 29 ft. lbf) Lower down the vehicle. Turn the ignition switch off. Check for fluid leaks in the transmission. If there are leaks, it is necessary to repair or replace O-rings, FIPGs, oil seals, plugs or other related parts. When adding a minimum amount of fluid: [*4] Using SST, create a short-circuit between terminals TC and CG of the DLC3. SST 09843-18040 Start the engine and run at idle. NOTE: The A/C switch must be turned off. Slowly move the shift lever from the P to the 2-L position. Return the shift lever to the P position. Switch to the fluid temperature detection mode. Move the shift lever from the N to the D position, or from D to N, within 1.5 seconds. (Repeat this operation for 6 seconds or more.) OK: The A/T OIL TEMP warning light comes on for 2 seconds and then goes off. Disconnect terminals TC and CG after confirming the above condition. Idle the engine to raise the fluid temperature. Lift up the vehicle immediately after the meter indicator light (ATF Temperature Warning Light) comes on. NOTE: Add fluid only when the meter indicator light is on. Perform this procedure while the engine is idling. Remove the overflow plug. If ATF overflows, proceed to [*5]. If ATF does not overflow, proceed to [*6]. HINT: "Overflow" indicates the condition under which ATF drains out from the overflow tube. When fluid overflows: [*5] Install the overflow plug with a new gasket when the draining ATF has become a trickle. Torque: 20 N.m (204 kgf° Cm, 15 ft. lbf) Install the refill plug with a new O-ring. Torque: 39 N.m (400 kgf° Cm, 29 ft. lbf) Lower down the vehicle. Turn the ignition switch off. Check for fluid leaks in the transmission. If there are leaks, it is necessary to repair or replace O-rings, FIPGs, oil seals, plugs or other related parts. When fluid does not overflow: [*6] Remove the refill plug. Add ATF through the refill hole until it drains out from the overflow hole. Install the overflow plug with a new gasket when the draining ATF has become a trickle. Torque: 20 N.m (204 kgf° Cm, 15 ft. lbf) Install the refill plug with a new O-ring. Torque: 39 N.m (400 kgf° Cm, 29 ft. lbf) Lower down the vehicle. Turn the ignition switch off. Check for fluid leaks in the transmission. If there are leaks, it is necessary to repair or replace O-rings, FIPGs, oil seals, plugs or other related parts.

DESCRIPTION

When troubleshooting On-Board Diagnostic (OBD II) vehicles, the vehicle must be connected to the OBD II scan tool (complying with SAE J1987). Various data output from the vehicle's ECM can then be read.

OBD II regulations require that the vehicle's on-board computer illuminates the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in

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1. The emission control system/components
2. The powertrain control components (which affect vehicle emissions)
3. The computer In addition, the applicable Diagnostic Trouble Codes (DTCs) prescribed by SAE J2012 are recorded in the ECM memory. If the malfunction does not reoccur in 3 consecutive trips, the MIL turns off automatically but the DTCs remain recorded in the ECM memory.

To check DTCs, connect the scan tool to the Data Link Connector 3 (DLC3) of the vehicle. The scan tool displays DTCs, the freeze frame data and a variety of the engine data. The DTCs and freeze frame data can be erased with the scan tool (See DTC CHECK / CLEAR ).

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Check mode has a higher sensitivity to malfunctions and can detect malfunctions that normal mode cannot detect. Check mode can also detect all the malfunctions that normal mode can detect. In check mode, DTCs are detected with 1-trip detection logic.

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1. Make sure that the items below are true: Battery positive voltage 11 V or more Throttle valve fully closed Transmission in the P or N position A/C switched OFF
2. Turn the ignition switch OFF.
3. Connect the hand-held tester together with the Controller Area Network Vehicle Interface Module (CAN VIM) to the DLC3.
4. Turn the ignition switch ON.
5. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / CHECK MODE.
6. Change the ECM to check mode. Make sure the MIL flashes as shown in the illustration. NOTE: All DTCs and freeze frame data recorded will be erased if: 1) the hand-held tester is used to change the ECM from normal mode to check mode or vice-versa; or 2) during check mode, the ignition switch is turned from ON to ACC or LOCK. Before check mode, make notes of the DTCs and freeze frame data.
7. Start the engine. The MIL should turn off after the engine starts.
8. Perform "MONITOR DRIVE PATTERN" for the ECT test (See «MONITOR DRIVE PATTERN»(ref-227567-S34715753032006040600000) ). (Or, simulate the conditions of the malfunction described by the customer).
9. After simulating the malfunction conditions, use the hand-held tester diagnosis selector to check the DTC and freeze frame data.

MONITOR DESCRIPTION

These DTCs indicate a problem with the park/neutral position switch and the wire harness in the park/neutral position switch circuit.

The park/neutral position switch detects the shift lever position and sends a signal to the ECM.

For security, the park/neutral position switch detects the shift lever position so that engine can be started only when the shift lever is in the P or N position.

The park/neutral position switch sends a signal to the ECM according to the shift position (NSW, R, D, 3 or 2).

The ECM determines that there is a problem with the switch or related parts if it receives more than 1 position signal simultaneously. The ECM will turn on the MIL and store the DTC.

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These DTCs indicate an open or short in the automatic transmission fluid (ATF) temperature sensor circuit. The automatic transmission fluid (ATF) temperature sensor converts ATF temperature to an electrical resistance value. Based on the resistance, the ECM determines the ATF temperature, and the ECM detects an open or short in the ATF temperature circuit. If the resistance value of the ATF temperature is less than 79ohm*1 or more than 156kohm*2, the ECM interprets this as a fault in the ATF sensor or wiring. The ECM will turn on the MIL and store the DTC.

*1: 150°C (302°F) or more is indicated regardless of the actual ATF temperature.

*2: -40°C (-40°F) is indicated regardless of the actual ATF temperature.

HINT

The ATF temperature can be checked on the OBD II scan tool or hand-held tester display.

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This DTC indicates that there is a problem with output from the automatic transmission fluid (ATF) temperature sensor and that the sensor itself is defective. The ATF temperature sensor converts the ATF temperature to an electrical resistance value. Based on the resistance, the ECM determines the ATF temperature and detects an open or short in the ATF temperature circuit or a fault in the ATF temperature sensor. After running the vehicle for a certain period, the ATF temperature should increase. If the ATF temperature is below 20°C (68°F) after running the vehicle for a certain period, the ECM interprets this as a fault, and turns on the MIL.

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This DTC indicates that pulse is not output from the speed sensor NT (Turbine (input) speed sensor) or is output only little. The NT terminal of the ECM detects the revolving signal from the speed sensor (NT) (input RPM). The ECM outputs a gearshift signal comparing the input speed sensor (NT) with the output speed sensor (SP2).

While the vehicle is operating in the 4th or 5th gear position in the shift position of D, if the input shaft revolution is less than 300 RPM *1 although the output shaft revolution is more than 1000 RPM or more *2 , the ECM detects the trouble, illuminates the MIL and stores the DTC.

*1: Pulse is not output or is irregularly output.

*2: The vehicle speed is approx. 50 km/h (31 mph) or more.

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The output speed sensor SP2 monitors the output shaft speed. The ECM controls the gearshift point and the lock up timing based on the signals from the output speed sensor SP2 and throttle position sensor. If the ECM detects no signal from the output shaft speed sensor SP2 even while the vehicle is moving, it will conclude that is a malfunction of the output speed sensor SP2. The ECM will illuminate the MIL and set a DTC.

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This DTC indicates that the stop light switch remains on. When the stop light switch remains ON during "stop and go" driving, the ECM interprets this as a fault in the stop light switch and the MIL comes on and the ECM stores the DTC. The vehicle must stop (less than 3 km/h (2 mph)) and go (30 km/h (19 mph) or more) ten times for two driving cycles in order to detect a malfunction.

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This DTC indicates an open or short in the shift solenoid valve SL1 circuit. The ECM commands gearshift by turning the shift solenoid valves "ON/OFF". When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. And the ECM performs the fail-safe function and turns the other normal shift solenoid valves "ON/OFF". (In case of an open or short circuit, the ECM stops sending current to the circuit.)

While driving and shifting between 4th and 5th gears, if the ECM detects an open or short in the shift solenoid valve SL1 circuit, the ECM determines there is a malfunction (See FAIL-SAFE CHART ).

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The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th or 5th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

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This DTC indicates "stuck ON malfunction" or "stuck OFF malfunction" of the shift solenoid valve S1. The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.

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The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th or 5th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

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This DTC indicates "stuck ON malfunction" or "stuck OFF malfunction" of the shift solenoid valve S2.

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.

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The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th or 5th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

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This DTC indicates "stuck ON malfunction" or "stuck OFF malfunction" of the shift solenoid valve SR or SL1.

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.

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The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th or 5th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

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This DTC indicates "stuck ON malfunction" or "stuck OFF malfunction" of the shift solenoid valve SL2.

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.

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This DTC indicates an open or short in the shift solenoid valve SL2 circuit. The ECM commands gear shift by turning the shift solenoid valves "ON/OFF". When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. And the ECM performs the fail-safe function and turns the other normal shift solenoid valves "ON/OFF". (In case of an open or short circuit, the ECM stops sending current to the circuit.)

While driving and shifting gears, if the ECM detects an open or short in the shift solenoid valve SL2 circuit, the ECM determines there is a malfunction (See FAIL-SAFE CHART ).

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

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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 (NCO) and the output speed sensor (SP2). The ECM can detect many mechanical problems in the shift solenoids, valve body, and the 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.

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These DTCs indicate an open or short in the shift solenoid valve S1 circuit. When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. When the shift solenoid valve S1 is on, if resistance is 8 ohm or less, the ECM determines there is a short in the shift solenoid valve S1 circuit.

When the shift solenoid valve S1 is off, if resistance is 100 kohm or more, the ECM determines there is an open in the shift solenoid valve S1 circuit (See FAIL-SAFE CHART ).

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These DTCs indicate an open or short in the shift solenoid valve S2 circuit. When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. When the shift solenoid valve S2 is on, if resistance is 8 ohm or less, the ECM determines there is a short in the shift solenoid valve S2 circuit.

When the shift solenoid valve S2 is off, if resistance is 100 kohm or more, the ECM determines there is an open in the shift solenoid valve S2 circuit (See FAIL-SAFE CHART ).

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These DTCs indicate an open or short in the shift solenoid valve SR circuit. When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. When the shift solenoid valve SR is on, if resistance is 8 ohm or less, the ECM determines there is a short in the shift solenoid valve SR circuit.

When the shift solenoid valve SR is off, if resistance is 100 k ohm or more, the ECM determines there is an open in the shift solenoid valve SR circuit (See FAIL-SAFE CHART ).

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The linear solenoid valve (SLT) controls the transmission line pressure for smooth transmission operation based on signals from the throttle position sensor and the vehicle speed sensor. The ECM adjusts the duty cycle of the SLT solenoid valve to control hydraulic line pressure coming from the primary regulator valve. Appropriate line pressure assures smooth shifting with varying engine outputs.

(*): Duty Ratio

The duty ratio is the ratio of the period of continuity in one cycle.

For example, if A is the period of continuity in one cycle, and B is the period of non-continuity, then

Duty Ratio = A/(A + B) x 100 (%)

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The ECM calculates the amount of heat absorbed by the friction material based on the difference in revolution (clutch slippage) between the turbine and output shaft. The ECM turns on the MIL and outputs this DTC when the amount of heat absorption exceeds the specified value.

When the shift solenoid valve SLT remains on, oil pressure goes down and clutch engagement force decreases.

Note. If you continue driving under these conditions, the clutch will burn out and the vehicle will no longer be drivable.

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When an open or short in the linear solenoid valve (SLT) circuit is detected, the ECM interprets this as a fault. The ECM will turn on the MIL and store the DTC.

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The Automatic Transmission Fluid (ATF) temperature sensor converts ATF temperature to an electrical resistance value. Based on the resistance, the ECM determines the ATF temperature, and the ECM detects an open or short in the AFT temperature circuit. If the resistance value of the ATF temperature is less than 25 ohm (0.046 V) or more than 156 kohm (4.915 V), the ECM interprets this as a fault in the ATF sensor or wiring. The ECM will turn on the MIL and store the DTC.

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The ECM uses the signals from the throttle position sensor, Airflow meter, turbine (input) speed sensor, output speed sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect a mechanical problems of the shift solenoid valve SLU, valve body and torque converter clutch.

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Torque converter lock-up is controlled by the ECM based on the turbine (input) speed sensor NT, output speed sensor SP2, engine RPM, engine load, engine temperature, vehicle speed, transmission temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine RPM (NE) to the input turbine RPM (NT). The ECM calculates the actual transmission gear by comparing input turbine RPM (NT) to output shaft RPM (SP2). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to the shift solenoid SLU. When the SLU is turned on, it applies pressure to the lock-up relay valve and locks the torque converter clutch.

If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in the shift solenoid valve SLU or lock-up system performance. The ECM will turn on the MIL and store the DTC.

Example

When any of the following is met, the system judges it as a malfunction.

1. There is a difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up. (Engine speed is at least 70 RPM greater than input turbine speed.)
2. There is no difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up off. (The difference between engine speed and input turbine speed is less than 35 RPM.)

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When an open or short in a shift solenoid valve (SLU) circuit is detected, the ECM determines there is a malfunction. The ECM will turn on the MIL and store this DTC.

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The ECM monitors the transfer-case L4 position switch to determine when the transfer-case L4 gear is engaged. If the transfer-case L4 gears remain engaged under the following conditions, the ECM will conclude that there is a malfunction of the L4 position switch

1. L4 switch indicated that the L4 transfer-case gears are engaged.
2. Transfer-case shifter is in the "H" position.
3. Transfer-case output shaft RPM is between 750 and 3,000 RPM.
4. The specified time period has elapsed. If all of the above conditions are detected, the ECM will conclude that there is a malfunction of the L4 switch, and illuminate the MIL and store the DTC.

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See also:
• ADJUSTMENT
• MIL CIRCUIT