1999 Lexus GS 400FACTORY OEM SERVICE PROCEDURE

Master Switch

Remove master switch. Check for continuity between specified terminals of master switch. See Fig 1. Ensure continuity is as specified in appropriate switch positions. See MASTER SWITCH CONTINUITY TESTΒ  table. If continuity is not as specified, replace master switch.

MASTER SWITCH CONTINUITY TEST

Position Terminals No.
Driver's Window
OFF (Neutral) (1)
UP 6 & 16
DOWN 16 & 18
AUTO 7 & 16
Front Passenger's Window
OFF (Neutral) (1)
UP 3 & 13
DOWN 3 & 4
AUTO 3 & 13
Left Rear Passenger's Window
OFF (Neutral) (1)
UP 12 & 14
DOWN 4 & 14
AUTO 13 & 14
Right Rear Passenger's Window
OFF (Neutral) (1)
UP 11 & 12
DOWN 4 & 11
AUTO 11 & 13
(1) Continuity should not be present between any terminals.
Fig 1: Identifying Master Switch Terminals
G98H03950Courtesy of Β© TOYOTA, LICENSE AGREEMENT TMS1002
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When to See a Mechanic

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

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.