Automatic Transmission System (A343E) (Diagnostic Codes): Overview Toyota 4Runner V

DESCRIPTION

The Park/Neutral Position (PNP) switch detects the shift lever position and sends signals to the ECM.

MONITOR DESCRIPTION

This DTC indicates a problem with the park/neutral position switch or 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 the engine can be started only when the shift lever is in P or N.

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

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 illuminate the MIL and store the DTC.

The ATF (Automatic Transmission Fluid) temperature sensor converts the ATF temperature into a resistance value which is input into the ECM.

The No. 2 Automatic Transmission Fluid (ATF) temperature sensor is on the transmission, just in front of the oil cooler inlet pipeline.

HINT

The temperature of the ATF easily rises when towing, climbing hills, in traffic, etc.

Vehicle conditions when the sensor is normal and when the sensor is short-circuited are indicated in the table below.

HINT

*: When the ATF temperature is normal, transmission lock-up occurs in 4th gear with the shift lever in D and in 3rd gear with the shift lever in 3.

The ATF temperature sensor converts the ATF temperature into 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. If the resistance value of the ATF temperature sensor is below 79 ohms or higher than 156 kohms, the ECM interprets this as a fault in the ATF sensor or wiring. The ATF temperature warning light blinks and the ECM stores the DTC.

Scheme 1160

This sensor detects the rotation speed of the turbine which indicates the input speed of the transmission. By comparing the input turbine speed signal NCO with the output speed sensor signal SP2, the ECM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions, and as a result, the gears shift smoothly.

Reference: Inspect using an oscilloscope.

Check the waveform of the ECM connector.

Standard

Scheme 1161

This DTC indicates that a pulse is not output from the speed sensor NCO (turbine (input) speed sensor) or is output only a little. The NCO terminal of the ECM detects the pulse signal from the speed sensor NCO (input turbine speed). The ECM outputs a gear shift signal by comparing the input speed sensor NCO signal with the output speed sensor SP2 signal.

If the input shaft speed is less than 300 RPM*1 although the output shaft speed is 500 RPM or more*2, the ECM detects the trouble, illuminates the MIL and stores the DTC.

HINT

1. *1: A pulse is not output or is irregularly output.
2. *2: The vehicle speed is approximately 50 km/h (30 mph) or more.

The speed sensor SP2 detects the rotation speed of the transmission output shaft and sends signals to the ECM. The ECM determines the vehicle speed based on these signals. An AC voltage is generated in the speed sensor SP2 coil as the parking gear mounted on the rear planetary gear assembly rotates, and this voltage is sent to the ECM.

The gear shift point and lock-up timing are controlled by the ECM based on the signals from this vehicle speed sensor and the throttle position sensor signal.

Reference: Inspect using an oscilloscope.

Check the waveform of the ECM connector.

Standard

Scheme 1162

The output speed sensor SP2 monitors the output shaft speed. The ECM controls the gear shift point and 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 speed sensor SP2 even while the vehicle is moving, it will conclude that there is a malfunction of the output speed sensor SP2. The ECM will illuminate the MIL and store the DTC.

The ECM uses signals from the output shaft speed sensor and input speed sensor 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 mechanical problems of the shift solenoid valves, valve body and automatic transmission (clutch, brake, gear, etc.).

HINT

Gear positions in the event of a solenoid valve mechanical problem

This DTC indicates a "stuck ON malfunction" or "stuck OFF malfunction" of 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.

The ECM uses signals from the output shaft speed sensor and input speed sensor 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 mechanical problems of the shift solenoid valves, valve body and automatic transmission (clutch, brake, gear, etc.).

HINT

Gear positions in the event of a solenoid valve mechanical problem

This DTC indicates a "stuck ON malfunction" or "stuck OFF malfunction" of 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.

Shifting from 1st to 4th is performed in combination with the ON and OFF operation of shift solenoid valves S1 and S2, which are controlled by the ECM. If an open or short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be operated safely. Also, the ECM stops sending current to the open or short-circuited solenoid. Refer to FAIL-SAFE CHART .

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

When shift solenoid valve S1 is OFF, if its resistance is 100 kohms or higher, the ECM determines there is an open in the shift solenoid valve S1 circuit. Refer to FAIL-SAFE CHART .

Shifting from 1st to 4th is performed in combination with the ON and OFF operation of shift solenoid valves S1 and S2, which are controlled by the ECM. If an open or short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be operated safely. Also, the ECM stops sending current to the open or short-circuited solenoid. Refer to FAIL-SAFE CHART .

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

When shift solenoid valve S2 is OFF, if its resistance is 100 kohms or higher, the ECM determines there is an open in the shift solenoid valve S2 circuit. Refer to FAIL-SAFE CHART .

With the shift lever in any forward position, when the difference in speed between the turbine and output shaft exceeds a specified value determined by the ECM (varies with output speed), the ECM illuminates the MIL and stores the DTC. When shift solenoid valve SLT remains on, the oil pressure and clutch engagement force decrease.

Refer to DTC P2714. Refer to DESCRIPTION .

Reference: Inspect using an oscilloscope.

Check the waveform of the ECM connector.

Standard

Scheme 1163

When an open or short in the shift solenoid valve SLT circuit is detected, the ECM interprets this as a fault. The ECM will illuminate the MIL and store the DTC.

The ATF (Automatic Transmission Fluid) temperature sensor converts the ATF temperature into a resistance value which is input into the ECM.

The ECM applies a voltage to the temperature sensor through ECM terminal THO1.

The sensor resistance changes with the ATF temperature.

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

The ECM calculates the ATF temperature based on the voltage signal.

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 sensor 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 of time, the ECM interprets this as a fault, turns on the MIL and stores the DTC.

When the ATF temperature is 110°C (230°F) or higher when the engine coolant temperature reaches 60°C (140°F) after a cold start, the ECM also determines this as a fault, turns on the MIL and stores the DTC.

Refer to DTC P2741. Refer to DESCRIPTION .

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 sensor circuit. If the resistance value of the ATF temperature sensor is below 79 ohms*1 or higher than 156 kohms*2, the ECM interprets this as a fault in the ATF temperature sensor or wiring. The ECM will illuminate the MIL and store the DTC.

HINT

1. *1: 150°C (302°F) or higher is indicated regardless of the actual ATF temperature.
2. *2: -40°C (-40°F) is indicated regardless of the actual ATF temperature.
3. The ATF temperature can be checked on the Techstream display.

The ECM 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 1164

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

Torque converter lock-up is controlled by the ECM based on the turbine (input) speed sensor NCO, output speed sensor SP2, engine speed, 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 speed (NE) to the input turbine speed (NCO). The ECM calculates the actual transmission gear by comparing the input turbine speed (NCO) to the output shaft speed (SP2). When conditions are appropriate, the ECM requests lock-up by applying control voltage to shift solenoid valve SLU. When shift solenoid valve 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 the lock-up system performance.

The ECM will illuminate the MIL and store the DTC.

Example

When one of the following conditions is met, the system determines that there is a malfunction.

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

The amount of current flow to the solenoid is controlled by the duty ratio* of the ECM output signal. During the lock-up operation, if the duty ratio increases, the lock-up hydraulic pressure increases.

HINT

*: The duty ratio is the ratio of the current ON time (A) to the total of the current ON and OFF time (A + B).

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

Reference: Inspect using an oscilloscope.

Check the waveform of the ECM connector.

Standard

Scheme 1165

When an open or short in the shift solenoid valve SLU circuit is detected, the ECM determines that there is a malfunction. The ECM will illuminate the MIL and store the DTC.