Disconnect sub-TP sensor connector. Loosen sub-TP sensor mounting screws. Remove sub-throttle actuator. Ensure sub-throttle valve is fully closed and sub-throttle valve gear is touching stop screw. Insert feeler gauge between gear and stop screw. See SUB-TP SENSOR ADJUSTMENT table.

Connect ohmmeter between terminals IDL2 and E2 of sub-TP sensor connector. See Figure. Rotate sub-TP sensor counterclockwise until there is no continuity, then rotate it clockwise until there is continuity. Tighten sub-TP sensor mounting screws. Inspect sub-TP sensor again.

SUB-TP SENSOR ADJUSTMENT

Application	Feeler Gauge Thickness
LS400	.012" (.30 mm)

Warm engine. Ensure idle speed is 650-750 RPM. Remove cap, filter and separator from end of dashpot. See Fig 1. Start engine and raise engine speed to 4000 RPM. Use finger to cover hole inside area where separator is normally installed in dashpot. Release throttle valve. This will fully extend dashpot rod. Check engine speed (ensure cooling fan is not running).
If engine speed (dashpot set speed) is not 2500 RPM, rotate dashpot adjusting screw as necessary. When installing separator, filter and cap, install filter with coarse side facing away from dashpot.

Fig 1: Identifying Dashpot Components

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Sub-Throttle Position (Sub-TP) Sensor: Adjustment

Use the Manual With the Right Hardware

When to See a Mechanic

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