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 shift solenoid valve SLN controls the hydraulic pressure acting on the accumulator control valve 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 direct clutch speed sensor and controls the volume of current flow to the solenoid valve. The amount of current to the solenoid is controlled by the (*) duty ratio of ECM output signals, causing a momentary charge to the hydraulic pressure acting on the clutches during gear shifting.

When the duty ratio is high, the hydraulic pressure acting on the clutches is low.

Fig 1: Identifying Accumulator Control Pressure And Current Flow To Solenoid Graph

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*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.

Fig 2: Duty Ratio In One Cycle

DTC CONDITION DETECTION CHART

DTC No	DTC Detecting Condition	Trouble Area
P2725	All condition below are detected 1 seconds or more. (1-trip detection logic) ECM outputs duty signal to shift solenoid valve SLN in 90 % or higher duty ratio Current to shift solenoid valve SLN: 230 - 430 mA or less	Open or short in shift solenoid valve SLN circuit Shift solenoid valve SLN ECM

Reference:

Refer to the chart for the waveform between terminals SLN^- and E1 when engine is idling.

Fig 3: Identifying Waveform Between Terminals SLN- and E1 (Engine Idling)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Refer to the chart for the waveform between terminals SLN^- and E1 during shift change.

Fig 4: Identifying Waveform Between Terminals SLN- and E1 (Shift Change)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002