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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: If not using the hand-held tester, start the inspection from step  2.
  1. Check the headlight relay using the hand-held tester. Connect the hand-held tester to the DLC3. See Figure. Check that the headlight relay can operate in an ACTIVE TEST. If the headlight relay is normal, the headlight comes ON. In the case that the headlight relay activates but the headlight will not come on, check the headlight circuit. If the results are OK, perform the next test procedure of the problem symptom. See step  4 of the SYSTEM OPERATION CHECK under TROUBLE SHOOTING. If the results are not good, go to the next step.
  2. Check the headlight relay. See 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 headlight relay.
  3. Check the wiring harness and connector between the headlight relay and body ECU, battery and headlight relay. If the results are OK, perform the next test procedure of the problem symptom. See step  4 of the SYSTEM OPERATION CHECK under TROUBLE SHOOTING. If the results are not good, repair or replace the wiring harness or connector.
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