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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 B1261/61: ECM 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 ECM by checking that the engine starts normally. With this inspection, ECM can be diagnosed if it works normally or not. If the result is OK, go to the next step. If the result is not good, replace the ECM. See ENGINE CONTROL MODULE (ECM)  under REMOVAL & INSTALLATION.
  2. Check the wiring harness by disconnecting the B5 connector of the body ECU No. 1, E5 of the ECM and A13 of the A/C amplifier. See CONNECTOR IDENTIFICATION .
    1. Check the continuity between terminals MPX1 of the body ECU No. 1 and MPX1 of the ECM. See WIRING DIAGRAMS .
    2. Check the continuity between terminals MPX2 of the ECM and MPX+ of the A/C amplifier.
    If there is an OPEN in the wiring harness of either step (A) or (B), repair it. If continuity exists in the wiring harness of both steps (A) and (B), or either (A) or (B), replace the ECM. See ENGINE CONTROL MODULE (ECM)  under REMOVAL & INSTALLATION. 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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