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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 133 (Multiplex Communication System) >> Diagnostic Tests >> DTC B1212: Front Passenger Door Ecu Communication Stopped >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Disconnect body ECU 18-pin harness connector B5, driver door ECU 20-pin harness connector D17 and front passenger door ECU 20-pin harness connector F13. See Figure. Backprobing, check continuity of Gray/Red wire between body ECU 18-pin harness connector B5 terminal No. 12 (MPX2 circuit) and front passenger door ECU 20-pin harness connector F13 terminal No. 7 (MPX1 circuit). Also, check continuity of Gray/Blue wire (MPX2 circuit) between front passenger door ECU 20-pin harness connector F13 terminal No. 8 and driver door ECU 20-pin harness connector D17 terminal No. 8 by backprobing. See Figure and Fig 1 . If continuity exists, go to next step. If continuity does not exist, repair identified circuit, harness or connector between body ECU and front passenger door ECU, or between front passenger door ECU and driver door ECU and retest system. See COMPUTER DATA LINES in SYSTEM WIRING DIAGRAMS article.
  2. With front passenger door ECU 20-pin harness connector F13 disconnected, check power feed circuits (BDR and CPUB) by backprobing between harness side of connector F13 terminals No. 9 (White/Red wire) and No. 10 (Blue/Orange wire) and good body ground point. See Figure. If 10-14 volts is present at both test points, go to next step. If 10-14 volts is not present at both test points, repair identified circuit, harness, connector or fuse(s) between front passenger door ECU and battery. See Fig 1.
  3. With front passenger door ECU 20-pin harness connector F13 disconnected, check ground circuit ("E") by backprobing between harness side of connector F13 terminal No. 2 (White/Black wire) and good body ground point. See Figure. If continuity does not exist, repair identified circuit, harness or connector between front passenger door ECU and vehicle ground point located on instrument panel reinforcement under right side of instrument panel. See Fig 1. If continuity exists, replace front passenger door ECU. See DRIVER DOOR ECU & FRONT PASSENGER DOOR ECU  under REMOVAL & INSTALLATION.
  4. After repairs have been made, perform confirmation test. See CONFIRMATION TEST  under SELF-DIAGNOSTIC SYSTEM.
Fig 1: Front Passenger Door ECU Wiring Diagram
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