Automatic Transaxle (Diagnostic Codes & Circuit Tests): Overview Lexus ES XV40 facelift

DESCRIPTION

The speed sensors detect the wheel speed and send the appropriate signals to the skid control ECU. The skid control ECU converts these wheel speed signals into a 4-pulse signal and outputs it to the TCM via the combination meter. The TCM determines the vehicle speed based on the frequency of these pulse signals.

Scheme 426

MONITOR DESCRIPTION

The TCM assumes that the vehicle is being driven when the transmission counter gear indicates more than 300 rpm and over 30 seconds have passed since the park/neutral position switch was turned off. If there is no signal from the vehicle speed sensor with these conditions satisfied, the TCM concludes that the vehicle speed sensor is malfunctioning. The TCM will turn on the MIL and a DTC will be set.

The battery supplies electricity to the TCM even when the engine switch is off. This power allows the TCM to store data such as DTC history, freeze frame data and fuel trim values. If the battery voltage falls below a minimum level, these memories are cleared and the TCM determines that there is a malfunction in the power supply circuit. When the engine is next started, the TCM will illuminate the MIL and set the DTC.

HINT

If DTC P0560 is set, the TCM does not store other DTCs.

While the engine is being cranked, the positive battery voltage is applied to terminal STA of the TCM.

If the TCM detects the Starter Control (STA) signal while the vehicle is being driven, it determines that there is a malfunction in the STA circuit. The TCM then illuminates the MIL and sets the DTC.

This monitor runs when the vehicle is driven at 12.4 mph (20 km/h) for over 20 seconds.

The TCM monitors its internal operation and it will set this DTC when it detects an internal malfunction.

The TCM monitors its internal operation. If the internal operation is malfunctioning, the TCM illuminates the MIL and sets a DTC.

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

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 TCM.

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 TCM according to the shift position (R or D). The TCM determines that there is a problem with the switch or related parts if it receives more than 1 position signal simultaneously. The TCM will turn on the MIL and store the DTC.

The ATF (Automatic Transmission Fluid) temperature sensor converts the fluid temperature into a resistance value for use by the TCM.

Scheme 427

The TCM applies a voltage to the temperature sensor through terminal OIL of the TCM.

The sensor resistance changes with the transmission fluid temperature. As the temperature becomes higher, the sensor resistance decreases.

One terminal of the sensor is grounded so that the sensor resistance decreases and the voltage goes down as the temperature becomes higher.

The TCM calculates the fluid temperature based on the voltage signal.

This DTC indicates that there is a problem with output signals from the automatic transmission fluid (ATF) temperature sensor and that the sensor itself is defective. The ATF temperature sensor converts the ATF temperature into an electrical resistance value. Based on the resistance, the TCM determines the ATF temperature and detects an open or short in the ATF temperature circuit or a fault of 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 TCM interprets this as a fault, and turns on the MIL.

The ATF (Automatic Transmission Fluid) temperature sensor converts the fluid temperature into a resistance value for use by the TCM.

The TCM applies a voltage to the temperature sensor through terminal OIL of the TCM.

The sensor resistance changes with the transmission fluid temperature. As the temperature becomes higher, the sensor resistance decreases.

One terminal of the sensor is grounded so that the sensor resistance decreases and the voltage goes down as the temperature becomes higher.

The TCM calculates the fluid temperature based on the voltage signal.

These DTCs indicate an open or short in the automatic transmission fluid (ATF) temperature sensor (TFT sensor) circuit. The automatic transmission fluid (ATF) temperature sensor converts ATF temperature into an electrical resistance value. Based on the resistance, the TCM determines the ATF temperature, and the TCM detects an open or short in the ATF temperature circuit. If the resistance value of the ATF temperature is less than 79 ohms *1 or more than 156 kohms *2 , the TCM interprets this as a fault in the ATF sensor or wiring. The TCM 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 Techstream display.

SYSTEM DESCRIPTION

This sensor detects the rotation speed of the turbine which shows the input revolution of transaxle. By comparing the input turbine speed signal (NT) with the counter gear speed sensor signal (NC), the TCM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions, thus, providing smooth gear shift.

Scheme 428

The NT terminal of the TCM detects a revolution signal from the speed sensor (NT) (input RPM). The TCM calculates a gearshift comparing the speed sensor (NT) with the speed sensor (NC).

While the vehicle is operating in 2nd, 3rd, 4th or 5th gear 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 1,000 rpm *2 , the TCM interprets this as a fault, illuminates the MIL and stores the DTC.

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

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

The purpose of this circuit is to prevent the engine from stalling while driving in lock-up condition when brakes are suddenly applied.

When the brake pedal is depressed, this switch sends a signal to the TCM. Then the TCM cancels the operation of the lock-up clutch while braking is in progress.

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

The TCM uses signals from the throttle position sensor, air-flow meter, turbine (input) speed sensor, intermediate (counter) speed sensor and crankshaft position sensor to help determine the engagement timing of the lock-up clutch. The TCM monitors the engagement of the clutch using the turbine (input) speed sensor, intermediate (counter) speed sensor and crankshaft position sensor.

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

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

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

HINT

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 TCM commands lock-up. (Engine speed is at least 70 rpm greater than the 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 TCM commands lock-up off. (The difference between the engine speed and input turbine speed is less than 20 rpm.)

The TCM uses the vehicle speed signal to determine the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

Then the TCM compares the actual gear with the shift schedule in the TCM memory to detect mechanical problems of the shift solenoid valves and valve body.

The TCM commands gear shifts by turning the shift solenoid valves on or off. According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the TCM detects the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear position). When the gear position commanded by the TCM and the actual gear position are not the same, the TCM illuminates the MIL.

Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1, SL2, SL3, SL4 and SL which is controlled by the TCM. If an open or short circuit occurs in any of the shift solenoid valves, the TCM controls the remaining normal shift solenoid valves to allow the vehicle to be operated smoothly. Refer to FAIL-SAFE CHART .

This DTC indicates an open or short in the shift solenoid valve SL1 circuit. The TCM causes gear shifts to occur by turning the shift solenoid valves on or off. When there is an open or short circuit in any shift solenoid valve circuit, the TCM detects the problem and illuminates the MIL and stores the DTC. The TCM also performs the fail-safe function and turns the other normal shift solenoid valves on or off. (In case of an open or short circuit, the TCM stops sending current to the circuit.)

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

The TCM uses the vehicle speed signal to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

Then the TCM compares the actual gear with the shift schedule in the TCM memory to detect shift solenoid valves and valve body mechanical problems.

The TCM commands gear shifts by turning the shift solenoid valves on or off. According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the TCM detects the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear position). When the gear position commanded by the TCM and the actual gear position are not the same, the TCM illuminates the MIL and stores the DTC.

Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1, SL2, SL3, SL4 and SL which is controlled by the TCM. If an open or short circuit occurs in any of the shift solenoid valves, the TCM controls the remaining normal shift solenoid valves to allow the vehicle to be operated smoothly. Refer to FAIL-SAFE CHART .

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

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

This sensor detects the rotation speed of the turbine which shows the input speed of transaxle. By comparing the input turbine speed signal (NC) with the counter gear speed sensor signal (NC), the TCM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions, thus, providing smooth gear shift.

The NT terminal of the TCM detects a revolution signal from the speed sensor (NT) (input RPM). The TCM calculates a gearshift comparing the speed sensor (NT) with the speed sensor (NC).

While the vehicle is operating in 2nd, 3rd, 4th or 5th gear 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 1,000 rpm *2 , the TCM interprets this as a fault, illuminates the MIL and stores the DTC.

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

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

The TCM uses the vehicle speed signal to determine the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

Then the TCM compares the actual gear with the shift schedule in the TCM memory to detect shift solenoid valves and valve body mechanical problems.

The TCM commands gear shifts by turning the shift solenoid valves on or off. According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the TCM detects the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear position). When the gear position commanded by the TCM and the actual gear position are not the same, the TCM illuminates the MIL and stores the DTC.

Shifting gears from 1st through 5th is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1, SL2, SL3 and SL4 which are controlled by the TCM. If an open or short circuit occurs in any of the shift solenoid valves, the TCM controls the remaining normal shift solenoid valves to allow the vehicle to be operated smoothly (Fail safe function).

The TCM commands gear shifts by turning the shift solenoid valves on or off. When there is an open or short circuit in any shift solenoid valve circuit, the TCM detects the problem and illuminates the MIL and stores the DTC. And the TCM performs the fail-safe function and turns the other normal shift solenoid valves on or off. (In case of an open or short circuit, the TCM stops sending current to the circuit.)

ATF pressure switch No. 1 is installed in the shift solenoid valve ATF output passage. This switch is used to identify the malfunctioning part when a fail-safe operation is performed. If the shift solenoid valve malfunctions when the ATF pressure switch has a malfunction, a fail-safe operation will be performed. This fail-safe operation is different from the fail-safe operation performed when the solenoid valve malfunctions and the ATF pressure switch is normal.

Scheme 429

ATF pressure switch No. 2 is installed in the shift solenoid valve ATF output passage. This switch is used to identify the malfunctioning part when a fail-safe operation is performed. If the shift solenoid valve malfunctions when the ATF pressure switch has a malfunction, a fail-safe operation will be performed. This fail-safe operation is different from the fail-safe operation performed when the solenoid valve malfunctions and the ATF pressure switch is normal.

Scheme 430

ATF pressure switch No. 3 is installed in the lock-up solenoid ATF output passage and is used to detect a malfunction in the lock-up solenoid.

The TCM illuminates the MIL and stores the DTC when the TCM detects that the ATF pressure switch is OFF with the lock-up solenoid ON or when the TCM detects that the ATF pressure switch is ON with the lock-up solenoid OFF.

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 TCM adjusts the duty ratio (*) 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 (%)

Scheme 431

The TCM calculates the amount of clutch slip based on the turbine speed, output shaft speed, and gear ratio. If the amount of clutch slip exceeds a specified level, the TCM will set this DTC and illuminate the MIL.

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

Note. If driving continues under these conditions, the clutches will burn out and the vehicle will no longer be drivable.

Refer to DTC P2714. Refer to SYSTEM DESCRIPTION .

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

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

Scheme 432

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

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

If the TCM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the TCM interprets this as a fault in shift solenoid valve SLU or lock-up system performance.

The TCM 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 (speed) between the input side (engine speed) and output side (input turbine speed) of the torque converter when the TCM commands lock-up. (Engine speed is at least 70 rpm greater than input turbine speed.)
2. There is no difference in rotation (speed) between the input side (engine speed) and output side (input turbine speed) of the torque converter when the TCM commands lock-up off. (The difference between engine speed and input turbine speed is less than 20 rpm.)

The amount of current flow to the solenoid is controlled by the (*) duty ratio of the TCM output signal. The higher the duty ratio becomes, the higher the lock-up hydraulic pressure becomes during the lock-up operation.

Scheme 433

(*) 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 (%).

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

The shift solenoid valve SL is turned ON or OFF by signals from the TCM to control the hydraulic pressure acting on the lock-up relay valve, which then controls operation of the lock-up clutch.

Fail-safe function

If the TCM detects a malfunction, it turns the shift solenoid valve SL OFF.

Based on the signals from the throttle position sensor, the air flow meter and the crankshaft position sensor, the TCM sends a signal to the solenoid valve SL to regulate the hydraulic pressure and provide smoother torque converter clutch engagement. The shift solenoid valve SL responds to commands from the TCM. The valve controls the lock-up relay valve to perform the torque-converter lock-up function. If the TCM detects an open or short circuit for shift solenoid valve SL, it will illuminate the MIL.

The TCM uses the vehicle speed signal to determine the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

Then the TCM compares the actual gear with the shift schedule in the TCM memory to detect shift solenoid valves and valve body mechanical problems.

The TCM commands gear shifts by turning the shift solenoid valves on or off. According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the TCM detects the actual gear position (1st, 2nd, 3rd, 4th or 5th gear position). When the gear position commanded by the TCM and the actual gear position are not the same, the TCM illuminates the MIL and stores the DTC.

Shifting gears from 1st through 5th is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1, SL2, SL3 and SL4 which are controlled by the TCM. If an open or short circuit occurs in either of the shift solenoid valve, the TCM controls the remaining normal shift solenoid valves to allow the vehicle to be operated smoothly (Fail safe function).

The TCM commands gear shifts by turning the shift solenoid valves on or off. When there is an open or short circuit in any shift solenoid valve circuit, the TCM detects the problem and illuminates the MIL and stores the DTC. And the TCM performs the fail-safe function and turns the other normal shift solenoid valves on or off. (In case of an open or short circuit, the TCM stops sending current to the circuit.)

The engine control unit intercommunicates with the TCM with the Controller Area Network (CAN).

If there is a problem in this intercommunication, the TCM sets a DTC.

When moving the shift lever into the S position using the transmission control switch, it is possible to switch the shift range position between "1" (first range) and "6" (sixth range).

Shifting up "+" once raises one shift range position, and shifting down "-" lowers one shift range position.

Scheme 434

Scheme 435

Scheme 436

1. CHECK HARNESS AND CONNECTOR (BATTERY - TRANSMISSION CONTROL SWITCH) Disconnect the transmission control switch connector of the shift lever assembly. Measure the voltage according to the value(s) in the table below. Standard voltage Tester Connection Switch Condition Specified Condition 3 - Body ground Engine switch on (IG) 11 to 14 V Engine switch off Below 1 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - BODY GROUND) Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition 5 - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
3. INSPECT TRANSMISSION CONTROL SWITCH Measure the resistance between each terminal of the shift lever assembly when the shift lever is moved to each position. Standard resistance Tester Connection Shift Position Specified Condition 3 - 7 S, "+" and "-" Below 1 ohms Except S, "+" and "-" 10 kohms or higher 2 - 5 Press continuously "+" (Up shift) Below 1 ohms S 10 kohms or higher 1 - 5 Press continuously "-" (Down shift) Below 1 ohms S 10 kohms or higher NG --> REPLACE TRANSMISSION CONTROL SWITCH OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM) Connect the transmission control switch connector of the shift lever assembly. Disconnect the A10 ECM connector. Turn the engine switch on (IG), and measure the voltage according to the value(s) in the table below when the shift lever is moved to each position. Standard voltage Tester Connection Shift Position Specified Condition A10-25 (S) - Body ground S, "+" and "-" 11 to 14 V Except S, "+" and "-" Below 1 V Turn the engine switch off. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below when the shift lever is moved to each position. Standard resistance Tester Connection Shift Position Specified Condition A10-16 (SFTU) - Body ground Press continuously "+" (Up shift) Below 1 ohms S 10 kohms or higher A10-51 (SFTD) - Body ground Press continuously "-" (Down shift) Below 1 ohms S 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN «PROBLEM SYMPTOMS TABLE»(ref-396631-S36747796032011050900000)

The park/neutral position switch detects the shift lever position and sends signals to the TCM.

Scheme 437

When the engine switch is turned on (IG), voltage from the ECM's MREL terminal is applied to the EFI relay. This causes the contacts of the EFI relay to close, which supplies power to terminal +B of the TCM.

Scheme 438

Scheme 439

Scheme 440

1. INSPECT ECU TERMINAL VOLTAGE (+B TERMINAL) Disconnect the TCM connector. Turn the engine switch on (IG). Measure the voltage according to the value(s) in the table below. Standard voltage Tester Connection Switch Condition Specified Condition B40-18 (+B) - B40-8 (E1) Engine switch on (IG) 9 to 14 V OK --> CHECK FOR INTERMITTENT PROBLEMS NG: Go to next step
2. CHECK HARNESS AND CONNECTOR (TCM - BODY GROUND) Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition B40-8 (E1) - Body ground Always Below 1 ohms Reconnect the TCM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (TCM - BODY GROUND) OK --> REPAIR OR REPLACE HARNESS OR CONNECTOR (TCM - EFI RELAY)