Electronic Controlled Automatic Transmission (ECT) - Diagnosis: Pre-Check

1. Description 
   • When troubleshooting vehicles with OBD II, the only difference from the usual troubleshooting procedure is that you connect an OBD II scan tool complying with SAE J1987 or LEXUS handheld tester to the vehicle, and read off various data output from the vehicle's ECM.
   • OBD II regulations require that the vehicle's on board computer lights up the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in the computer itself or in drive system components which affect vehicle emissions. In addition to the MIL lighting up when a malfunction is detected, the applicable DTCs prescribed by SAE J2012 are recorded in the ECM memory (See FUEL SYSTEM ).

     If the malfunction only occurs in 3-trips, the MIL goes off but the DTCs remain recorded in the ECM memory.

     Fig 1: Identifying Malfunction Indicator Lamp

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • To check the DTCs, connect an OBD II scan tool or LEXUS hand held tester to DLC3 on the vehicle. The OBD II scan tool or LEXUS hand held tester also enables you to erase the DTCs and check freeze frame data and various forms of engine data (For instruction book).
   • DTCs include SAE controlled codes and Manufacturer controlled codes.

     SAE controlled codes must be set as the codes prescribed by the SAE, while Manufacturer controlled codes can be set freely by the manufacturer within the prescribed limits (See DIAGNOSTIC TROUBLE CODE CHART ).

   • The diagnosis system operates in normal mode during normal vehicle use, and also has a check mode for technicians to simulate malfunction symptoms and perform troubleshooting. Most DTCs use 2-trip detection logic (*) to prevent erroneous detection. By switching the ECM to check mode when troubleshooting, the technician can cause the MIL to light up for a malfunction that is only detected once or momentarily (LEXUS hand held tester) (See FUEL SYSTEM ).
   • *2-trip detection logic:

     When a logic malfunction is first detected, the malfunction is temporarily stored in the ECM memory. If the same malfunction is detected again during the 2nd test drive, this 2nd detection causes the MIL to light up. The 2-trip repeats the same mode 2nd time (However, the IG switch must be turned OFF between the 1st trip and 2nd trip.).

2. Inspect the DLC3.

   The vehicle's ECM uses the ISO 9141-2 communication protocol. The terminal arrangement of DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

Fig 2: Identifying DLC3 Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

• If communication is normal when the tool is connected to another vehicle, inspect DLC3 on the original vehicle.
• If communication is still not possible when the tool is connected to another vehicle, the problem is probably in the tool itself, so consult the Service Department listed in the tool's instruction manual.

1. Check the MIL.
   1. The MIL comes on when the ignition switch is turned ON and the engine is not running.
      NOTE: If the MIL does not light up, troubleshoot the combination meter (See INDICATORS AND WARNING LIGHT DOES NOT LIGHT UP ).
   2. When the engine is started, the MIL should go off. If the lamp remains on, the diagnosis system has detected a malfunction or abnormality in the system.
   Fig 3: Identifying Malfunction Indicator Lamp

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Check the DTC.
   NOTE: LEXUS hand held tester only: When the diagnostic system is switched from normal mode to check mode, it erases all DTCs and freeze frame data recorded in normal mode. So before switching modes, always check the DTCs and freeze frame data, and note them down.
   1. Prepare an OBD II scan tool (complying with SAE J1978) or LEXUS hand held tester.
   2. Connect the OBD II scan tool or LEXUS hand held tester to DLC3 at the lower of the instrument panel.
   3. Turn the ignition switch ON and turn the OBD II scan tool or LEXUS hand held tester switch ON.
   4. Use the OBD II scan tool or LEXUS hand held tester to check the DTCs and freeze frame data and note them down (For operating instructions, see the OBD II scan tool's instruction book).
   5. See DIAGNOSTIC TROUBLE CODE CHART  to confirm the details of the DTCs.

1. Check the DTC.
   1. Check the initial conditions.
      • Battery positive voltage 11 V or more
      • Throttle valve fully closed
      • Transmission in P position
      • Air conditioning switched OFF
   2. Turn the ignition switch OFF.
   3. Prepare a LEXUS hand held tester.
   4. Connect the LEXUS hand held tester to DLC3 at the lower side of the instrument panel.
   5. Turn the ignition switch ON and switch the LEXUS hand held tester ON.
   6. Switch the LEXUS hand held tester from Normal mode to Check mode (Check that the MIL flashes).
   7. Start the engine (MIL goes out after the engine starts).
   8. Simulate the conditions of the malfunction described by the customer.
      NOTE: Leave the ignition, switch ON until you have checked the DTCs, etc.
   9. After simulating the malfunction conditions, use the LEXUS hand held tester diagnosis selector to check the DTCs and freeze frame data, etc.
      Fig 4: Identifying Malfunction Indicator Lamp Flashing Pattern

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      NOTE: Take care not to turn the ignition switch OFF, as turning it off the diagnosis system switches Check mode to Normal mode, so all DTCs, etc. are erased.
   10. After checking the DTC, inspect the applicable circuit.
2. Clear the DTC.

   The following operation will erase the DTC and freeze frame data. Operating an OBD II scan tool (complying with SAE J1978) or LEXUS hand held tester to erase the codes (See the OBD II scan tool's instruction book for operating instructions.).

1. D position test (NORM and PWR pattern):

   Shift into the D position and fully depress the accelerator pedal and check the following points.

   1. Check up shift operation.

      Check to see that 1 --> 2, 2 --> 3, 3 --> 4 and 4 --> 5th up-shifts take place, and that the shift points conform to the automatic shift schedule .

      NOTE:

      • 5th Gear Up-shift Prohibition Control (1. Coolant temp, is 55 °C (128 °F) or less. 2. Vehicle speed is 51 km/h (32 mph) or less.)
      • 5th Gear Lock up Prohibition Control (1. Brake pedal is depressed. 2. Coolant temp. is 60 °C (140 °F) or less.)
   2. Check for shift shock and slip.

      Check for shock and slip at the 1 --> 2, 2 --> 3, 3 --> 4 and 4 --> 5th up-shifts.

   3. Check for abnormal noises and vibration.

      Drive in the D position lock up or 5th gear and check for abnormal noises and vibration.

      NOTE: The check for the cause of abnormal noises and vibration must be done very thoroughly as it could also be due to loss of balance in the differential, torque converter clutch, etc.
   4. Check kick-down operation.

      While running in the D position, 2nd, 3rd, 4th and 5th gears, check to see that the possible kick-down vehicle speed limits for 2 --> 1, 3 --> 2, 4 --> 3 and 5th --> 4 kick-downs conform to those indicated on the automatic shift schedule.

   5. Check abnormal shock and slip at kick-down.
   6. Check the lock up mechanism.
      • Drive in D position 5th gear, at a steady speed (lock up ON) of about 70 km/h (43 mph).
      • Lightly depress the accelerator pedal and check that the engine speed does not change abruptly.

   If there is a big jump in engine speed, there is no lock up.

2. 4 position test:

   Shift into the 4 position and fully depress the accelerator pedal and check the following points.

   1. Check up shift operation.

      Check to see that the 1 --> 2, 2 --> 3 and 3 --> 4 up shift takes place and that the shift point conforms to the automatic shift schedule.

      NOTE: There is no 5th up shift in the 4 position.
   2. Check engine braking.

      While driving in the 4 position and 4th gear, release the accelerator pedal and check the engine braking effect.

   3. Check for abnormal noises during acceleration and deceleration, and for shock at up shift and down-shift.
3. 3 position test:

   Shift into the 3 position and fully depress the accelerator pedal and check the following points.

   1. Check up shift operation.

      Check to see that the 1 --> 2 and 2 --> 3 up shift takes place and that the shift point conforms to the automatic shift schedule.

   2. Check engine braking.

      While running in the 3 position and 3rd gear, release the accelerator pedal and check the engine braking effect.

   3. Check for abnormal noises during acceleration and deceleration, and for shock at up shift and down-shift.
4. 2 position test:

   Shift into the 2 position and fully depress the accelerator pedal and check the following points.

   1. Check up shift operation.

      Check to see that the 1 --> 2 up shift takes place and that the shift point conforms to the automatic shift schedule.

   2. Check engine braking.

      While running in the 2 position and 2nd gear, release the accelerator pedal and check the engine braking effect.

   3. Check for abnormal noises during acceleration and deceleration, and for shock at up shift and down-shift.
5. L position test:

   Shift into the L position and fully depress the accelerator pedal and check the following points.

   1. Check no up shift.

      While running in the L position, check that there is no up shift to 2nd gear.

   2. Check engine braking.

      While running in the L position, release the accelerator pedal and check the engine braking effect.

   3. Check for abnormal noises during acceleration and deceleration.
6. R position test:

   Shift into the R position and fully depress the accelerator pedal and check for slipping.

   CAUTION: Before conducting this test ensure that the test area is free from people and obstruction.
7. P position test:

   Stop the vehicle on a grade (more than 5°) and after shifting into the P position, release the parking brake. Then, check to see that the parking lock pawl holds the vehicle in place.

1. You are able to set the A/T gear position as you like by operating each solenoid valve forcibly using OBD II scan tool or LEXUS hand held tester.

However, the condition that you can set the gear position differs in the setting gear position, so perform the ACTIVE TEST following conditions in the table below.

1. Measure the stall speed.

   The object of this test is to check the overall performance of the transmission and engine by measuring the stall speeds in the D position.

   NOTE:

   • Do the test at normal operating fluid temperature 50 - 80 °C (122 -176 °F).
   • Do not continuously run this test for longer than 5 seconds.
   • To ensure safety, conduct this test in a wide, clear level area which provides good traction.
   • The stall test should always be carried out in pairs. One technician should observe the conditions of wheels or wheel stoppers outside the vehicle while the other is doing the test.
   • Chock the 4 wheels.
   • Connect an OBD II scan tool or LEXUS hand held tester to DLC3.
   • Fully apply the parking brake.
   • Keep your left foot depressing firmly on the brake pedal.
   • Start the engine.
   • Shift into the D position. Press all the way down on the accelerator pedal with your right foot. Quickly read the stall speed at this time.

   Stall speed: 

   2,450 +/- 150 rpm (In D position) 

   Evaluation: 

   STALL SPEED EVALUATION
   
   

   Problem	Possible cause
   Stall speed low in D position	Engine output may be insufficient Stator one-way clutch is operating properly NOTE: If more than 600 rpm below the specified value, the torque converter clutch could be faulty.
   (b) Stall speed high in D position	Line pressure too low Forward clutch slipping No. 2 one-way clutch not operating properly O/D one-way clutch not operating properly

2. Measure the time lag.

   When the shift lever is shifted while the engine is idling, there will be a certain time lapse or lag before the shock can be felt. This is used for checking the condition of the O/D direct clutch, forward clutch, and 1st & reverse brake.

   NOTE:

   • Do the test at normal operating fluid temperature 50 - 80 °C (122 -176 °F).
   • Be sure to allow 1 minute interval between tests.
   • Take 3 measurements and take the average value.
3. Fully apply the parking brake.
4. Start the engine and check idle speed.

Idle speed (In H position and air conditioner OFF): 

750 +/- 50 rpm 

• Shift the shift lever from N to D position. Using a stop watch, measure the time from when the lever is shifted until the shock is felt.

Time lag: N --> D Less than 1.2 seconds 

• In the same manner, measure the time lag for N --> R.

Time Sag: N --> R Less than 1.5 seconds 

Evaluation (If N --> D time or N --> R time lag is longer than the specified): 

1. Measure the line pressure.
   NOTE:

   • Do the test at normal operation fluid temperature 50 - 80 °C (122 -176 °F). 
   • The line pressure test should always be carried out in pairs. One technician should observe the conditions of wheels or wheel stoppers outside the vehicle while the other is doing the test. 
   • Be careful to prevent SST's hose from interfering with the exhaust pipe. 
   1. Warm up the ATR
   2. Remove the test plug on the front left side of the transmission case and connect SST.

      SST 09992-00095 (09992-00231, 09992-00271)

   3. Fully apply the parking brake and chock the 4 wheels.
   4. Start the engine and check idling speed.
   5. Keep your left foot pressing firmly on the brake pedal and shift into D position.
   6. Measure the line pressure when the engine is idling.
   7. Depress the accelerator pedal all the way down. Quickly read the highest line pressure when engine speed reaches stall speed.
   8. In the same manner, do the test in R position.
   Fig 5: Connecting SST

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Specified line pressure: 

If the measured pressures are not up to the specified values, recheck the throttle cable adjustment and re-test.

Evaluation: 

1. Disconnect the solenoid wire.
2. Inspect the manual driving operation.

   Check that the shift and gear positions correspond to the table below.

   While driving, shift through the L, 2, 3, 4 and D positions. Check that the gear change corresponds to the shift position.

   Fig 6: Identifying Electronic Controlled Automatic Transmission

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   SHIFT POSITION AND GEAR POSITION SPECIFICATIONS
   
   

   Shift Position	Gear Position
   D	5th
   4	5th
   3	4th
   2	3rd
   L	3rd
   R	Reverse
   P	Pawl Lock

   NOTE: If the L, 2, 3, 4 and D gear positions are difficult to distinguish, do the above read test.

   If any abnormality is found in the above test, the problem is in the transmission itself.

3. Connect the solenoid wire.
4. Clear out the DTC.