1990 Lexus LS 400FACTORY OEM SERVICE PROCEDURE

LS400 (Normal Mode)

  1. Normal Mode is used for routine testing of vehicle. To read diagnostic codes, ensure battery voltage is at least 11 volts, throttle valve is fully closed, transmission is in Neutral and all accessories are off.
  2. The Total Diagnostic Communication Link (TDCL) connector is located under left side of instrument panel. See Fig 1. Diagnostic codes can be obtained through TDCL connector or check connector. On LS400, check connector is located near top front of engine. See Fig 2.
  3. Turn ignition on. DO NOT start engine. Using a jumper, wire connect terminals E1 and TE1 together either on TDCL connector or check connector. See Figure. Count number of flashes from CHECK engine light.
  4. If CHECK engine light flashes 2 times every second, this indicates system is normal. If a diagnostic code is displayed, first group of flashes will provide first digit of a 2-digit diagnostic code. There will be a 1.5 second delay between first digit and second digit of diagnostic code. The second group of flashes will equal second digit of diagnostic code.
  5. If more than one code is stored, there will be a 2.5 second delay between diagnostic codes. After all diagnostic codes have been displayed, a 4.5 second delay will occur, then diagnostic codes will be repeated until jumper wire connecting terminals E1 and TE1 is disconnected. Diagnostic codes will display from smallest to largest number.
  6. Record diagnostic codes. See DIAGNOSTIC CODE IDENTIFICATION table for description of possible circuit problem. After reading diagnostic code description, see appropriate diagnostic code chart. To clear codes, see CLEARING CODES in this article.
Fig 1: Locating TDCL Connector
G90H18884Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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