Troubleshooting automatic transmission [Toyota Corona T190]

Note:

• When fault codes appear (2WD models) no. 37, 38, 42, 61, 62 and 63 or (4WD models) #62, 63 indicator will start flashing immediately to alert the driver. However, a collision or impact may cause the indicator to stop flashing, but the fault codes will be stored in the memory of the automatic transmission control unit until they are forcibly reset.
• The occurrence of fault codes No.64 and 68 does not cause the warning indicator to flash.
• If the speed sensor fails, the fault code will not appear and the self-diagnosis system will not work. However, when the selector is in the "O" position, the movement will only occur in first gear, regardless of the vehicle speed.

Code 37 (A245E): Speed Sensor Circuit #2

1. Measure the voltage between the terminals "NC2+" and "NC2-" of the automatic transmission control unit connector and the engine. If the voltage is normal, replace the control unit.

2. Check speed sensor #2 Replace the faulty sensor.

3. Check the connector and wiring between the sensor and the automatic transmission control unit and the engine.

Code 38 (A245E): Working fluid temperature sensor circuit

1. Measure the voltage between the terminals "TNO" and "E1" of the automatic transmission control unit connector and the engine. If the voltage is normal, replace the control unit.

2. Check the working fluid temperature sensor. Replace the faulty sensor.

3. Check the connector and wiring between the sensor and the automatic transmission control unit.

Code 42: Speed Sensor Circuit (instrument cluster)

1. Measure the voltage between the terminals "SPD" and "E1" of the automatic transmission control unit connector. If the voltage is normal, replace the control unit.

2. Check the speed sensor. Replace the faulty sensor.

3. Check the ABS system. Repair the faulty ABS system.

4. Check the instrument cluster. Replace the faulty instrument cluster.

3. Check the wiring between the control unit and the instrument cluster.

Code 44 (A540H): Gearbox Rear Output Shaft Speed Sensor Circuit

1. Measure the conductivity between the terminals "RR+" and "RR-" of the automatic transmission control unit connector and the engine. If there is conductivity, replace the automatic transmission control unit and the engine.

2. Check the gearbox rear output shaft speed sensor. Replace the faulty sensor.

3. Check the wiring between the automatic transmission control unit and the sensor.

Code 61 (models before 1996.): speed sensor circuit #2

1. Measure the conductivity between the SP2 terminal of the control unit connector and the ground. If there is conductivity, replace the automatic transmission and engine control unit.



2. Check speed sensor #2. Replace the faulty sensor.

3. Check the wiring between the control unit and the speed sensor.

Code 61 (A540H): Front Output Shaft Speed Sensor Circuit

1. Check the conductivity between the terminals "FR*" and "FR" of the automatic transmission control unit connector and the engine and the engine. If there is conductivity, replace the automatic transmission control unit.

2. Check the front output shaft speed sensor of the gearbox. Replace the faulty sensor.

3. Check the wiring between the automatic transmission control unit and the speed sensor.

Code 62: Solenoid Valve Circuit #1

1. Measure the resistance of the electromagnetic valve No.1 on the automatic transmission control unit connector. If the resistance is normal, replace the automatic transmission control unit

2. Remove the oil pan and measure the resistance between the connector of the electromagnetic valve No.1 and the "ground". If the resistance is not normal, replace the electromagnetic valve No.1. Normal resistance is 11-15 Ohm

3. Check the wiring between solenoid valve No.1 and the automatic transmission control unit.

Code 63: Solenoid Valve Circuit #2

1. Measure the resistance of the electromagnetic valve #2 on the automatic transmission and engine control unit connector. If the resistance is normal, replace the control unit.

2. Remove the oil pan and measure the resistance between the connector of the electromagnetic valve #2 and the ground. If the resistance is not normal, replace the valve #2. Normal resistance. 11-15 Ohm.



3. Check the wiring between solenoid valve #2 and the control unit.

Code 64: Torque Converter Lockup Clutch Control Solenoid Circuit

1. Measure the resistance of the electromagnetic valve on the connector of the automatic transmission and engine control unit. If the resistance is normal, replace the control unit.

2. Remove the oil pan and measure the resistance between the solenoid valve connector and ground. If the resistance is not normal, replace the solenoid valve. Normal resistance is 11-15 Ohms.

3. Check the wiring between the solenoid valve and the control unit.

Code 68 (A245E): Torque Converter Lock-Up Quality Control Solenoid Valve Circuit

1. Measure the voltage at the terminals "SLU+" and "SLU-" of the automatic transmission control unit connector. If the voltage is normal, replace the control unit.

2. Check the solenoid valve. Replace the faulty solenoid valve.

3. Check the wiring between the solenoid valve and the control unit.

Code 73 (A540K): Interaxle Differential Lock Control Solenoid Valve Circuit

1. Measure the resistance of the electromagnetic valve on the automatic transmission control unit connector. If the resistance is normal, replace the control unit.

2. Remove the oil pan and measure the resistance between the solenoid valve connector and ground. If the resistance is not normal, replace the solenoid valve. Normal resistance is 11-15 ohms.

3. Check the wiring between the solenoid valve and the control unit.

Code 77 (A540H): Main Line Pressure Regulating Solenoid Valve Circuit

1. Measure the resistance of the electromagnetic valve on the connector of the automatic transmission and engine control unit. If the resistance is normal, replace the control unit.



2. Remove the oil pan and measure the resistance between the solenoid valve connector and ground. If the resistance is not normal, replace the solenoid valve. Normal resistance is 11-15 ohms.

3. Check the wiring between the solenoid valve and the control unit.