LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 1994 >> SC 400 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Fuel System >> Fuel Injector Circuit
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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" (Black/Red, Black, Black/Yellow and Yellow wires). To identify ECM connectors and terminals, see Figure.
  3. If battery voltage is measured at all terminals, go to next step. If battery voltage is not measured 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 there is no continuity, repair open White/Black wires. If there is continuity, 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.
scientia non olet · About LEMON Manuals