SYSTEM DESCRIPTION
- 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, and controls the shift point, based on driver habits and road conditions. As a result, fuel efficiency and power transaxle performance are improved. Shift shock has been reduced by controlling the engine and transaxle simultaneously. In addition, the ECT has features such as follows: Diagnostic function Fail-safe function when a malfunction occurs
DESCRIPTION
The park/neutral position switch detects the shift lever position and sends signals to the ECM.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0705 | (A) Any 2 or more signals of the following are ON simultaneously (2-trip detection logic) STAR input signal is ON. R input signal is ON. D input signal is ON. 2 input signal is ON. L input signal is ON. (B) Any 2 or more signals of the following are ON simultaneously (2-trip detection logic) P input signal is ON. R input signal is ON. N input signal is ON. D input signal is ON. 2 input signal is ON. L input signal is ON. (C) All switches are OFF simultaneously for P, R, N, D, 2 and L positions (2-trip detection logic) (D) Both 1 and 2 are met (2-trip detection logic) One of following is met STAR input signal is ON. P input signal is ON. R input signal is ON. N input signal is ON. One of following is ON. 3 input signal is ON. | Open or short in park/neutral position switch circuit Park/neutral position switch ECM |
DTC DETECTION CONDITION CHART
MONITOR DESCRIPTION
The park/neutral position switch detects the gearshift position and sends a signal to the ECM.
For security, the park/neutral position switch detects the gearshift position so that engine can be started only when the vehicle is in P or N shift position.
When the park/neutral position switch sends more than one signal at a time from switch positions P, R, N, D, 3, 2 or L the ECM interprets this as a fault in the switch. The ECM will turn on the MIL.
The ATF (Automatic Transmission Fluid) temperature sensor converts the fluid temperature into a resistance value which is input into the ECM.
The ECM applies a voltage to the temperature sensor through ECM terminal THO1 (THO).
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 ECM calculates the fluid temperature based on the voltage signal.
Scheme 1
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0710 | (a) and (b) are detected momentarily within 0.5 sec. when neither P0712 nor P0713 is detected (1-trip detection logic) ATF temperature sensor resistance is less than 79 ohms. ATF temperature sensor resistance is more than 156 kohms. HINT: Within 0.5 sec, the malfunction switches from (a) to (b) or from (b) to (a) | Open or short in ATF temperature sensor circuit Transmission wire (ATF temperature sensor) ECM |
| P0712 | ATF temperature sensor resistance is less than 79 ohms for 0.5 sec. or more (1-trip detection logic) | Short in ATF temperature sensor circuit Transmission wire (ATF temperature sensor) ECM |
| P0713 | ATF temperature sensor resistance is more than 156 kohms when 15 minutes or more have elapsed after the engine start DTC is detected for 0.5 sec. or more (1-trip detection logic) | Open in ATF temperature sensor circuit Transmission wire (ATF temperature sensor) ECM |
DTC DETECTION CONDITION CHART
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 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 ohms *1 or more than 156 kohms *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 Techstream display.
The ATF (Automatic Transmission Fluid) temperature sensor converts the fluid temperature into a resistance value which is input into the ECM.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0711 | Either of the following Condition (A) or (B) is met: Condition (A): All of (a), (b) and (c) are detected (2-trip detection logic): Intake air and engine coolant temperatures are more than -10°C (14°F) at engine start. After normal driving for over 5 minutes and 5.6 miles (9 km) or more, ATF temperature is less than 20°C (68-F). 19 minutes or more have elapsed after engine start. Condition (B): Both (a) and (b) are detected (2-trip detection logic) Engine coolant temperature is less than 35°C (95°F) at engine start. ATF temperature is 100°C (212°F) or more when engine coolant temperature reaches 60°C (140°F). | ATF level Transmission wire (ATF temperature sensor) ECM |
DTC DETECTION CONDITION CHART
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 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 20°C (68°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 100°C (212°F) or more and engine coolant temperature reaches 60°C (140°F) after cold start, the ECM also determines this as a fault, turns on the MIL, and stores the DTC.
This sensor detects the rotation speed of the input turbine. By comparing the input turbine speed signal (NT) with the output shaft speed, the ECM 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.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0717 | ECM detects conditions (a), (b) and (c) continuously for 5 sec. or more: (1 -trip detection logic) Vehicle speed: 50 km/h (31 mph) or more Park/neutral position switch (STAR, R and L) is OFF Speed sensor (NT): less than 300 rpm | Open or short in transmission revolution sensor NT (speed sensor NT) circuit Transmission revolution sensor NT (speed sensor NT) ECM Automatic transaxle assembly |
DTC DETECTION CONDITION CHART
The input speed sensor detects the transmission input shaft speed. The ECM determines the gear shift timing based on a comparison of the input speed sensor (input shaft speed) with the output speed sensor (output shaft speed).
When the output shaft speed is higher than the expected value and the input shaft speed is 300 rpm or less while running with the shift in the D position, the ECM will conclude that there is malfunction of the input turbine speed sensor (NT). The ECM will illuminate the MIL.
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 signals to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0724 | The stop light switch remains ON even when the vehicle is driven in a STOP (less than 3 km/h (2 mph) and GO (30 km/h (19 mph) or more) fashion 5 times. (2-trip detection logic). | Short in stop light switch circuit Stop light switch ECM |
DTC DETECTION CONDITION CHART
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 a malfunction.
The ECM uses signals from the vehicle speed sensor and speed sensor NT to detect the actual gear position (1st, 2nd, 3rd or 4th gear).
Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect the mechanical problems of the shift solenoid valves, the valve body or automatic transaxle (clutch, brake or gear etc.).
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0751 | The gear required by the ECM does not match the actual gear when driving (2-trip detection logic) | Shift solenoid valve S1 remains open or closed Valve body is blocked Shift solenoid valve S1 Automatic transaxle (clutch, brake or gear etc.) |
DTC DETECTION CONDITION CHART
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 4th 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 and speed sensor NT to detect the actual gear position (1st, 2nd, 3rd or 4th gear).
Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect the mechanical problems of the shift solenoid valves, the valve body or automatic transaxle (clutch, brake or gear etc.).
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0756 | The gear required by the ECM does not match the actual gear when driving (2-trip detection logic) | Shift solenoid valve S2 remains open or closed Valve body is blocked Shift solenoid valve S2 Automatic transaxle (clutch, brake or gear etc.) |
DTC DETECTION CONDITION CHART
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 4th 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.
Shift solenoid valve ST is switched ON-OFF by a signal from ECM so that let in or out timing of 2nd brake is adjusted by operating orifice control valve. Therefore, shift solenoid valve ST operates when letting in or out reverse clutch. If the shift solenoid valve ST is broken, the shift shock becomes big.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0787 | ECM detects short in solenoid valve ST circuit 2 times when solenoid valve ST is operated (1-trip detection logic) | Short in shift solenoid valve ST circuit Shift solenoid valve ST ECM |
| P0788 | ECM detects open in solenoid valve ST circuit 2 times when solenoid valve ST is not operated (1 -trip detection logic) | Open in shift solenoid valve ST circuit Shift solenoid valve ST ECM |
DTC DETECTION CONDITION CHART
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 the MIL comes on. Illuminating the MIL, the ECM performs the fail-safe 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.).
Shifting from 1st to 4th is performed in combination with "ON" and "OFF" of the shift solenoid valve S1 and S2 controlled by ECM. If an open or short circuit occurs in either of the solenoid valves, the ECM controls the remaining normal solenoid valve to allow the vehicle to be operated smoothly (Fail safe function).
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0973 | ECM detects short in solenoid valve S1 circuit 2 times when solenoid valve S1 is operated (1-trip detection logic) | Short in shift solenoid valve S1 circuit Shift solenoid valve S1 ECM |
| P0974 | ECM detects open in solenoid valve S1 circuit 2 times when solenoid valve S1 is not operated (1-trip detection logic) | Open in shift solenoid valve S1 circuit Shift solenoid valve S1 ECM |
DTC DETECTION CONDITION 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 ).
Shifting from 1st to 4th is performed in combination with "ON" and "OFF" of the shift solenoid valve S1 and S2 controlled by ECM. If an open or short circuit occurs in either of the solenoid valves, the ECM controls the remaining normal solenoid valve to allow the vehicle to be operated smoothly (Fail safe function).
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0976 | ECM detects short in solenoid valve S2 circuit 2 times when solenoid valve S2 is operated (1-trip detection logic) | Short in shift solenoid valve S2 circuit Shift solenoid valve S2 ECM |
| P0977 | ECM detects open in solenoid valve S2 circuit 2 times when solenoid valve S2 is not operated (1-trip detection logic) | Open in shift solenoid valve S2 circuit Shift solenoid valve S2 ECM |
DTC DETECTION CONDITION 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 shift 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 ratio (*) of the shift solenoid valve SLT 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 2
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P2714 | ECM detects a malfunction on SLT (ON side) according to the revolution difference of the turbine, intermediate and the output shaft, and also by the oil pressure. (2-trip detection logic) | Shift solenoid valve SLT remains closed Valve body is blocked Torque converter clutch Automatic transaxle (clutch, brake or gear, etc.) |
DTC DETECTION CONDITION CHART
In any forward position, when the difference between the revolutions of the turbine, Intermediate and output shaft exceeds the specified value (varies with Intermediate, output speed) determined by the ECM, the ECM illuminates the MIL and store the DTC.
When shift solenoid valve SLT remains on, the oil pressure goes down and the 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.
The shift 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 shift solenoid valve SLT 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 (%)
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P2716 | Open or short is detected in shift solenoid valve SLT circuit for 1 second or more while driving (1-trip detecting logic). | Open or short in shift solenoid valve SLT circuit Shift solenoid valve SLT ECM |
DTC DETECTION CONDITION CHART
Scheme 3
When an open or short in the shift 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 lock-up is controlled by the ECM based on the speed sensor (NT), engine rpm (NE), engine load, engine coolant temperature, vehicle speed, transmission fluid 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 speed. When conditions are appropriate, the ECM requests lock-up by applying the control voltage to shift solenoid valve SLU. When 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 shift solenoid valve SLU or lock-up system performance.
The ECM turns on the MIL and stores the DTC.
Example
When either of the following is met, the system judges it as a malfunction.
- There is a difference in the rotations of 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 100 rpm greater than input turbine speed.)
- There is no difference in the rotations of 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.)
When an open or short in the shift solenoid valve SLU circuit is detected, the ECM interprets this as a fault. The ECM will turn on the MIL and stores the DTC.
See also:
• REGISTRATION
• REMOVAL
• REMOVAL