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Home › Lexus › 2006 › SC 430 › Repair and Diagnosis › Transmission › Automatic Trans › Electronic Controlled Automatic Transmission (ECT) -- Diagnostics › Mechanical System Tests

Mechanical System Tests

  1. MEASURE STALL SPEED 
    1. The purpose of this test is to check the overall performance of the transmission and engine by measuring the stall speeds when the shift lever is on D.
      NOTE:
      • Perform the test at the normal operating ATF temperature of 50 to 80°C (122 to 176°F).
      • Do not continuously run this test longer than 5 seconds.
      • To ensure safety, conduct this test in a wide, clear and level area with good traction.
      • The stall test should always be performed by at least 2 people. One person should observe the condition of the wheels or wheel chocks while the other is performing the test.
      1. Chock the 4 wheels.
      2. Connect the hand-held tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
      3. Fully apply the parking brake.
      4. Keep your left foot firmly on the brake pedal.
      5. Start the engine.
      6. Move the shift lever to D. Fully press the accelerator pedal with your right foot and immediately read the stall speed.

      Stall speed: 2,400 +/- 150 rpm 

      Evaluation: 

      PROBLEM CHART

      Problem Possible Cause
      Stall engine speed is low when shift lever is on D
      • Engine power output may be insufficient*
      • Stator one-way clutch not operating properly*
      Stall engine speed is high when shift lever is on D
      • Line pressure too low
      • Forward clutch slipping
      • No. 2 one-way clutch not operating properly
      • O/D one-way clutch not operating properly
      HINT:
      *: If the value is higher or lower than the specified value by 600 rpm or more, the torque converter clutch may be malfunctioning.
  2. MEASURE TIME LAG 
    1. When the shift lever is moved 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:
      • Perform the test at the normal operating ATF temperature of 50 to 80°C (122 to 176°F).
      • Be sure to wait 1 minute between tests.
      • Perform each measurement 3 times and take the average value.
      1. Connect the hand-held tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
      2. Fully apply the parking brake.
      3. Start the engine and check idle speed.

        Idle speed: approx. 700 rpm (shift lever on N and A/C OFF) 

      4. Move the shift lever from N to D. Using a stopwatch, measure the time from when the lever is moved until the shock is felt.

        Time lag: N to D is less than 1.2 seconds 

      5. In the same manner, measure the time lag for N to R.

        Time lag: N to R is less than 1.5 seconds 

        Evaluation: 

        PROBLEM CHART

        Problem Possible Cause
        N to D time lag is longer than specified
        • Line pressure too low
        • Forward clutch worn
        • O/D one-way clutch not operating properly
        N to R time lag is longer than specified
        • Line pressure too low
        • Direct clutch worn
        • 1st & reverse brake worn
        • O/D one-way clutch not operating properly
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