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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.
  1. Check the continuity of the RR WIPER, RADIO No. 2, DOOR and GAUGE fuses. If there is continuity, go to the next step. If there is not continuity, replace the failure fuse.
  2. Turn the ignition switch ON. Measure voltage between terminals B5-8 (WIG), B8-18 (ACC), B8-5 (IG), and B5-9 (GND1), B8-2 (GND2). See CONNECTOR IDENTIFICATION . Voltage is OK if there is 10-14 Volts. Turn the ignition switch OFF. Disconnect the body ECU connector. Measure the voltage between terminals B8-4 (BSUB), B5-2 (BECU) and B5-9 (GND1), B8-2 (GND2). Voltage is OK if there is 10-14 Volts. 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.
  3. Check the wiring harness and connector between the body ECU and body ground. If the results are OK, check and repair the wiring harness and connector between the body ECU and battery. If the results are not good, repair or replace the wiring harness or connector.
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