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Home >> Toyota >> 2004 >> Matrix Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 159 (Multiplex Communication System) >> Diagnostic Tests >> DTC B1271/71: Instrument Panel Ecu Communication Stopped >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Lexus GS 430, 2003 Lexus GS 300, 2002 Lexus GS 430, and 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check the instrument panel ECU by starting the engine and check that the speed meter and tachometer operate normally. With this inspection, the instrument panel ECU can be diagnosed if it works normally or not. If the results are OK, go to the next step. If the results are not good, replace the instrument panel ECU. See INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.
  2. Check the wiring harness by disconnecting the connector B6 of the body ECU No. 2, C13 of the instrument panel ECU and C8 of the air bag sensor assembly. See CONNECTOR IDENTIFICATION .
    1. Check the continuity between terminals MPX2 of the body ECU No. 2 and MPX- of the instrument panel ECU. See WIRING DIAGRAMS .
    2. Check the continuity between terminals MPX+ of the instrument panel ECU and MPX2 of the air bag sensor assembly.
    If there is an OPEN in the wiring harness of either step (A) or (B), repair it. If there is continuity in the wiring harness of both (A) and (B), or either (A) or (B), replace the instrument panel ECU. See INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT. If the results are not good, repair or replace the wiring harness. See WIRING DIAGRAMS .
  3. After repairs have been made, perform confirmation test. See CONFIRMATION TEST  under SELF-DIAGNOSTIC SYSTEM.
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