1995 Lexus SC 400FACTORY OEM SERVICE PROCEDURE

Fuel Injector Circuit

  1. Turn ignition off. Pull back the right front floor mat. Remove ECM protective cover. Connect Check Harness (09990-01000) between ECM and harness. See USING CHECK HARNESS  under INTRODUCTION. Turn ignition on.
  2. Measure voltage between chassis ground and terminals No. 17-20 of ECM connector "B". To identify ECM connectors and terminals, see Figure.
  3. If battery voltage is present at all terminals, go to next step. If battery voltage is not present at all terminals, check ignition main relay. See RELAYS  under MODULES, MOTORS, RELAYS & SOLENOIDS. If ignition main relay is okay, repair harness between ignition main relay and battery.
  4. Check for continuity between chassis ground and terminals No. 79 and 80 (White/Black wires) of ECM connector "B". If continuity does not exist, repair open White/Black wires. If continuity exists, check for open circuits between ignition main relay and injectors, and between injectors and ECM.
  5. If circuits are okay, measure injector resistance and volume. See FUEL INJECTOR RESISTANCE  and FUEL INJECTOR VOLUME. If resistance and volume are as specified, replace ECM.
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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