AT2–75 A340E (2JZ—GTE) AUTOMATIC TRANSMISSION – TROUBLESHOOTING DTC 46 No.4 Solenoid Valve Circuit (For Accumulator Back Pressure Modulation) CIRCUIT DESCRIPTION The No.4 solenoid valve controls the hydraulic pressure acting on the brakes and clutches of the planetary gear units when gears are shifted and performs smooth gear shifting. The ECM determines optimum operating pressure according to the signals from the throttle position sensor, vehicle speed sensor and O/D clutch speed sensor and controls the volume of current flow to the solenoid valve. The amount of electric current to the solenoid is controlled by the (*) duty ratio of ECM output signals, causing momentary change to the hydraulic pressure acting on the clutches during gear shift- ing. When the duty ratio is high, the hydraulic pressure acting on the clutches is now. (*) 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) × 100 (%) ON A B OFF 1 cycle BE4056 Lock–up operation pressure Current flow to solenoid DTC No. | Diagnostic Trouble Code Detection Condition | Trouble Area 46 | All conditions below are detected for 1 sec. or more. (2 trips detection logic)* (a) ECM outputs duty signal to No.4 solenoid in 90% or higher duty ratio. (b) Current to No.4 solenoid: 330 ± 100 mA or less (O/D OFF indicator light doesn't blink) | No. 4 solenoid valve Harness or connector between No.4 solenoid valve and ECM ECM * See page AT2–58 <Reference> Waveform between terminals SLN and E1 when engine is idling. AT8764 5 V/div. GND 1 msec./division Waveform between terminals SLN and E1 during shift change. AT8766 5 V/div. GND 1 msec./division