1999 Lexus SC 400FACTORY OEM SERVICE PROCEDURE

Ignition Timing: Es300

  1. Remove intake manifold cover. See Figure. Start engine and warm engine to normal operating temperature. Shut engine off. Connect scan tool to data link connector No. 3. See Fig 1. Scan tool is used to read engine RPM.
  2. Connect timing light lead to Black/Red at ignition coil electrical connector on top of front valve cover at cylinder No. 4. See Fig 2. Cylinder No. 4 is second cylinder on left side when viewed from flywheel end of engine. See Figure.
  3. Apply parking brake. Place transaxle in Neutral. Start engine and maintain engine at 2500 RPM for 90 seconds and allow engine to idle. Ensure idle speed is 650-750 RPM.
  4. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 on data link connector No. 1. See Fig 3. Data link connector No. 1 is located on end of air intake chamber at passenger's side of engine compartment.
  5. Timing marks are located on timing belt cover, near crankshaft pulley. Ensure base timing is 8-12 degrees BTDC at idle with transaxle in Neutral, and with A/C and all accessories off.
  6. Remove jumper wire from data link connector No. 1. Ensure ECM controlled timing is 10-25 degrees BTDC. Shut engine off. Remove timing light and scan tool. Reinstall intake manifold cover.
    Fig 1: Connecting Scan Tool To Data Link Connector No. 3 (ES300)
    G99F50414Courtesy of © 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:

  • • 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.