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HOMESERVICE MANUALSLEXUS1998GS 300REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SYSTEM/COMPONENT TESTSFUEL SYSTEMFUEL PUMP OPERATIONUSING LEXUS SCAN TOOL
1998 Lexus GS 300

Using Lexus Scan Tool

1998 Lexus GS 300SECTION Using Lexus Scan Tool
  1. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Turn scan tool on. DO NOT  start engine.
  2. Select ACTIVE TEST mode on scan tool. Using Lexus scan tool manufacturer's instructions, activate electric fuel pump. On all models except SC400, fuel pump is operating if fuel pump operating sound can be heard or pulsations can be felt in fuel line near fuel filter. On GS300, check that fuel pressure pulsation damper screw rises when fuel pump operates. See Fig 1.
  3. If fuel pump does not operate, check for faulty fusible link in engine compartment fuse/relay block, located at left side of engine compartment. Check for faulty AM2 (30-amp) in engine compartment fuse/relay block, located at left side of engine compartment, and IGN (5-amp) in instrument panel fuse block, located at left side of steering wheel. Check for faulty EFI main relay in engine compartment junction block, located at left front of engine compartment. Check for faulty fuel pump, ECM or poor wiring connections.
Fig 1: Identifying Fuel Pressure Pulsation Damper Screw
G98E10425Courtesy 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.