Circuit Description

WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

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

This controls the line pressure and provides smooth shifting characteristics.

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

*Duty Ratio

Fig 1: Line And Control Pressure Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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: Identifying Duty Ratio In One Cycle

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DTC CONDITION DETECTION CHART

DTC No.	DTC Detection Condition	Trouble Area
P2716	ECM detects solenoid SLT circuit malfunction for 1 sec. or more (1-trip detection logic)	Open or short in shift solenoid valve SLT circuit Shift solenoid valve SLT ECM

Reference:

Refer to the chart for the waveform between terminals SLT⁺ and SLT^- during engine idling.

Fig 3: Identifying Waveform