Inspection Procedure

WARNING: This page is about a different car, the 2003 Lexus IS 300 and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The inspection procedure is based on the premise that the taillights light up normally whenever the light control switch is operated. If taillight operation is not normal when the light control switch is operated, proceed to PROBLEM SYMPTOM INDEX table.

NOTE: If not using the hand-held tester, start the inspection from step 2.

Connect the hand-held tester to the DLC3. See Figure. Check that the taillight relay can operate in an ACTIVE TEST. If the taillight relay is normal, the taillights come ON. If the taillight relay activates but the taillights will not come on, check the taillight circuit. If the results are OK, proceed to the next circuit inspection of the symptom. See PROBLEM SYMPTOM INDEX table. If the results are not good, go to the next step.
Disconnect the theft deterrent ECU connector. Measure the voltage between terminal T5-2 (TAIL) of the theft deterrent ECU and body ground. See CONNECTOR IDENTIFICATION . If voltage is between 10-14 volts, check and replace the theft deterrent ECU. If the voltage is not as specified, check and repair the harness and connector between the theft deterrent ECU and taillight control relay.