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Home >> Lexus >> 2003 >> RX 300 AWD >> Repair and Diagnosis (Single Page) >> Body & Frame >> Door Locks >> Engine Immobilizer >> Diagnostic Tests >> B2785/99: Ignition Switch On Malfunction & B2786/99: Ignition Switch Off Malfunction >> Diagnostic Procedure

Diagnostic Procedure

  1. Remove the glove compartment. Turn the ignition switch ON. Measure the voltage by connecting the positive (+) lead to terminal No. E5-16 (+B) and the negative (-) lead to terminal No. E8-17 (E1) of the ECM connector. See CONNECTOR IDENTIFICATION . If the voltage is between 9-14 volts, proceed to the next circuit inspection of the symptom. See PROBLEM SYMPTOM INDEX  table. If the voltage is not as specified, go to the next step.
  2. Check for an open in the harness and connector between terminal No. E8-17 (E1) of the ECM and body ground. If the results are OK, go to the next step. If the results are not good, repair or replace the harness or connector.
  3. Check the electronic fuel injection (EFI) main relay. See RELAYS under RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If the results are OK, go to the next step. If the results are not good, replace the EFI main relay located in the engine room junction block.
  4. Check the EFI fuse. Remove the EFI fuse from the engine room junction block and check the continuity. If there is continuity, go to the next step. If there is not continuity, check for a short in all the harnesses and components connected to the EFI fuse.
  5. Check for an open harness and connector between EFI main relay and battery, EFI main relay and ECM. If the results are OK, go to the next step. If the results are not good, repair or replace the harness or connector.
  6. Remove the IGN fuse from the instrument panel junction block. Check the continuity of the EGN fuse. If there is continuity, go to the next step. If there is not continuity, check for a short in all the harness and components connected to the IGN fuse.
  7. Check the ignition switch. See IGNITION SWITCH under COMPONENT TESTS in STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. If the results are OK, go to the next step. If the results are not good, replace the ignition switch. See appropriate STEERING COLUMN article.
  8. Check for an open circuit in the harness and connector between the IG switch and EFI main relay, EFI main relay and body ground. If the results are OK, replace the ECM. See ENGINE CONTROL MODULE (ECM)  under REMOVAL & INSTALLATION. If the results are not good, repair or replace the wiring harness and connector.
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