Automatic Transmission Electronic Controlled (ECT) - U241E/U140F - Diagnostics: Overview Toyota Highlander I рестайлинг

SYSTEM DESCRIPTION

1. SYSTEM DESCRIPTION The ECT (Electronic controlled automatic transmission/transaxle) is an automatic transmission/transaxle that electronically controls shift timing using the ECM. The ECM detects electrical signals that indicate engine and driving conditions, controls the shift point, and selects the appropriate shift pattern based on driver habits and road conditions. As a result, fuel efficiency and power transmission/transaxle performance are improved. Shift shock has been reduced by controlling the engine and transmission/transaxle simultaneously. In addition, the ECT has the following features: Diagnostic function. Fail-safe function when a malfunction occurs.

MONITOR DESCRIPTION

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 opens or shorts in the ATF temperature circuit. If the resistance value of the ATF temperature is less than 79 ohm *1 or more than 156 kQ *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.

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 opens or shorts 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 10°C (50°F) after running the vehicle for a certain period, the ECM interprets this as a fault, and turns on the MIL.

When the ATF temperature is 110°C (230°F) or more after 17 minutes of engine cold start, the ECM also determines this as a fault, turns on the MIL, and stores the DTC.

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

While the vehicle is operating in 2nd, 3rd or O/D 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 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 50 km/h (31 mph) or more.

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) 5 times for two driving cycles in order to detect malfunction.

The ECM uses the signals from the throttle position sensor, Air-flow meter, turbine (input) speed sensor, intermediate (counter) shaft speed sensor and crankshaft position sensor to monitor the engagement condition of the lockup clutch.

Then the ECM compares the engagement condition of the lockup clutch with the lockup schedule in the ECM memory to detect a mechanical problems of the shift solenoid valve DSL, valve body and torque converter clutch

Scheme 172

Torque converter lockup is controlled by the ECM based on speed sensor (NT), speed sensor (NC), engine RPM, engine load, engine temperature, vehicle speed, transmission temperature, and gear selection. The ECM determines the lockup 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 counter gear RPM (NC). When conditions are appropriate, the ECM requests "lockup" by applying control voltage to shift solenoid DSL. When the DSL is turned on, solenoid DSL applies pressure to the lockup relay valve and locks the torque converter clutch.

If the ECM detects no lockup after lockup has been requested or if it detects lockup when it is not requested, the ECM interprets this as a fault in the shift solenoid valve DSL or lockup 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 before and after torque converters even when the ECM commands lockup. (Engine speed is at least 75 RPM greater than input turbine speed.)
2. There is no difference in rotation between before and after torque converters even when the ECM commands lockup off. (The difference between engine speed and input turbine speed is less than 35 RPM.)

The ECM uses signals from the vehicle speed sensor to detect the actual gear position (1 st, 2nd, 3rd or O/D 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 and valve body.

Scheme 173

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the ECM detects the actual gear position (1st, 2nd, 3rd or O/D gear position). When the gear position commanded by the ECM and the actual gear position are not same, the ECM illuminates the MIL.

Example: When either condition (a) or (b) is met, the ECM detects a malfunction.

1. The ECM commands the 1 st gear, but the actual gear is 2nd.
2. The ECM commands the 2nd gear, but the actual gear is 1st.

The ECM commands gear shifts 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 shift solenoid valves in good condition "ON/OFF" (In case of an open or short circuit, the ECM stops sending current to the circuit.) (See FAIL-SAFE CHART ).

The ECM uses signals from the vehicle speed sensor to detect the actual gear position (1st, 2nd, 3rd or O/D 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 and valve body.

Scheme 174

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the ECM detects the actual gear position (1st, 2nd, 3rd or O/D gear position). When the gear position commanded by the ECM and the actual gear position are not same, the ECM illuminates the MIL and stores the DTC.

The ECM uses signals from the vehicle speed sensor to detect the actual gear position (1st, 2nd, 3rd or O/D 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 and valve body.

Scheme 175

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". According to the input shaft revolution, intermediate (counter) shaft revolution and output shaft revolution, the ECM detects the actual gear position (1st, 2nd, 3rd or O/D gear position). When the gear position commanded by the ECM and the actual gear position are not same, the ECM illuminates the MIL and stores the DTC.

MONITOR DESCRIPTION CHART

The ECM commands gear shifts 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 shift solenoid valves in good condition "ON/OFF" (In case of an open or short circuit, the ECM stops sending current to the circuit.) (See FAIL-SAFE CHART ).

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

While the vehicle is operating in 2nd, 3rd or O/D gear in the shift position of D, if the counter gear revolution is less than 300 RPM *1 although the output shaft revolution is more than 1,000 RPM *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 50 km/h (31 mph) or more.

The ECM commands gear shifts 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 shift solenoid valves in good condition "ON/OFF" (In case of an open or short circuit, the ECM stops sending current to the circuit.) (See FAIL-SAFE CHART ).

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.

Torque converter lockup is controlled by the ECM based on engine RPM, engine load, engine temperature, vehicle speed, transmission temperature, and shift range selection. The ECM determines the lockup 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 counter gear RPM (NC). When conditions are appropriate, the ECM requests "lockup" by applying control voltage to shift solenoid DSL. When the DSL is opened, solenoid DSL applies pressure to the lockup relay valve and locks the torque converter clutch. If the ECM detects an open or short in the DSL solenoid circuit, the ECM interprets this as a fault in the DSL solenoid or circuit. The ECM will turn on the MIL and store the DTC.