1993 Lexus SC 300 AutomaticFACTORY OEM SERVICE PROCEDURE

Test Mode

  1. This mode detects same malfunctions as normal mode. It also detects malfunctions in starter signal circuit, No. 1 and No. 2 cam position sensors (if equipped), idle contact signal of TPS, A/C signal, neutral start switch signal (M/T) and park/neutral start switch (A/T). Test mode is more sensitive to intermittent and regular faults and is used for road test conditions.
  2. 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. Turn ignition off. Locate Data Link Connector No. 2 (DLC2). See Figure. Using a jumper wire, connect terminals E1 and TE2 of DLC2. See Figure. Turn ignition on. DO NOT  start engine.
    NOTE: If terminals E1 and TE2 are connected after ignition is turned on, test mode will not start.
  3. When ignition is turned on, Malfunction Indicator Light (MIL) on instrument panel should flash. If MIL does not flash, see MALFUNCTION INDICATOR LIGHT (MIL) DOES NOT FLASH .
  4. Start engine. Perform road test and simulate conditions described by customer. DO NOT  disconnect jumper wire connecting terminals E1 and TE2. After road test, connect another jumper wire between terminals E1 and TE1 of DLC No. 1 or 2.
  5. Count number of flashes from MIL. System is functioning properly (normal condition) if MIL flashes 2 times every second. If a diagnostic trouble code is displayed, first group of flashes will indicate first digit of a 2-digit diagnostic code. After a 1.5 second delay, second group of flashes will indicate second digit of diagnostic code.
  6. If more than one code is stored, a 2.5 second delay will occur between diagnostic codes. After all diagnostic codes have been displayed, a 4.5 second delay will occur and then codes will be repeated until jumper wire connecting terminals E1 and TE1 is disconnected. Diagnostic codes will display from smallest to largest number.
  7. After completing check, disconnect terminals TE1 and TE2 from terminal E1 on DLC. Diagnostic Code 43 will set if engine is not cranked when entering test mode. This is normal. When vehicle speed is less than 3 MPH, Code 42 will set (ES300). This is normal. If automatic transmission is in "D", 2, "L" or "R", A/C switch is in ON position or accelerator pedal is depressed, Code 51 will set. This is normal.
  8. Identify and record diagnostic trouble codes. See DIAGNOSTIC TROUBLE CODES  for description of condition(s) that caused code to set and probable trouble area. Identify code in TROUBLE CODE IDENTIFICATION  table and go to appropriate diagnostic code chart. To clear codes, see CLEARING CODES .
Factory Service Tools

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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.

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