Circuit Description

The throttle pressure that is applied to the primary regulator valve (which modulates the line pressure) causes the solenoid valve SLT, under electronic control, to precisely and minutely modulate and generate the line pressure according the extent of the accelerator pedal depressed or the output of engine power.

This reduces the function of the line pressure and provides smooth shifting.

Fig 1: Liner Solenoid Duty Ratio

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Upon receiving a signal of the throttle valve opening angle, the ECM controls the line pressure by sending a predetermined duty ratio to the solenoid valve, modulating the line pressure and generating throttle pressure.

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) x 100 (%).

Fig 2: Linear Solenoid Malfunction DTC Chart

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Fig 3: Checking Waveform Between Terminal SLT+ During Engine Idle

Reference:

Check the waveform between terminals SLT+ and SLT- during the engine idling.