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Home >> Lexus >> 2006 >> IS 250 RWD, Standard >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Automatic Transmission (A960E)) >> Automatic Transmission System >> DTC P0766 Shift Solenoid "D" Performance (Shift Solenoid Valve S4) >> System Description

System Description

WARNING: This page is about a different variant/trim than selected.

The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).

DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
P0766 "S4 stuck OFF malfunction", "SL2 stuck ON malfunction" or "Brake control valve malfunction"*1 :
Shifting to 5th and 6th gears is impossible.
The ECM determines there is a malfunction when the following conditions are both met.(2-trip detection logic)
  1. When the ECM directs the gearshift to switch to 5th gear, the actual gear is shifted to 4th.
  2. When the ECM directs the gearshift to switch to 6th gear, the actual gear is shifted to 4th.
  • Shift solenoid valve S4 remains closed
  • Shift solenoid valve SL2 remains open
  • Shift solenoid valve SLT remains open or closed
  • Valve body is blocked (Brake control valve)
  • Automatic transmission (clutch, brake or gear, etc.)

HINT:

GEAR POSITION DURING FAIL-SAFE OPERATION

Gear position under normal conditions 1st 2nd 3rd 4th 5th 6th
*1: Actual gear position under fail-safe mode       3rd 3rd 3rd