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HOMESERVICE MANUALSTOYOTA2004MATRIX XR, FWD, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 777 (MULTIPLEX COMMUNICATION SYSTEM - DIAGNOSIS)CIRCUIT INSPECTIONINSPECTION PROCEDURE
2004 Toyota Matrix XR, FWD, Standard

Inspection Procedure

2004 Toyota Matrix XR, FWD, StandardSECTION Inspection Procedure
WARNING: This page is about a different car, the 2004 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check power window master switch ECU 

    CHECK: 

    Check if the driver door window glass auto up

    HINT:

    With this inspection, power window master switch CPU can be diagnosed if it works normally or not

    1. NG: Replace the power window master switch 
    2. OK: Go to next step. 
  2. Check wire harness 

    PREPARATION: 

    Disconnect connector of body ECU and "P9" of Power window master switch

    CHECK: 

    Check continuity between terminals MPX3 of body ECU and TX of power window master switch

    OK: 

    there is a continuity in wire harness

    HINT:

    If there is OPEN in wire harness, please repair it

    1. NG: Repair or replace wire harness 
    2. OK: Go to next step. 

    Replace the power window master switch 

    Fig 1: Checking Continuity Between Terminals MPX3 Of Body ECU & TX Of Power Window Master Switch
    G01497313Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002


  1. Check the communication circuit inside power window master switch ECU 

    PREPARATION: 

    Disconnect connector of body ECU and "P9" of Power window master switch

    CHECK: 

    Check the DTC

    OK: 

    Code B1214/14 or B1215/15 is not output

    Fig 1: Disconnecting Connector Of Body ECU & P9 Of Power Window Master Switch
    G01497315Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. OK: replace the power window master switch 
    2. NG: Go to next step. 
  2. Check for short circuit between power window master switch and body ECU 

    PREPARATION: 

    1. Connect the connector of "P9" of Power window master switch
    2. Disconnect the connector of body ECU

      HINT:

      Connector is disconnected by removing body ECU form driver side junction block

    CHECK: 

    Check the DTC

    OK: 

    Code B1214/14 or B1215/15 is not output

    1. OK: replace the wire harness between power window master switch and body ECU 
    2. NG: Go to next step. 

    Replace the body ECU 

    Fig 2: Disconnecting Connector Of Body ECU
    G01497316Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002


  1. Check wire harness 

    PREPARATION: 

    Disconnect the connector of tuner and body ECU

    CHECK: 

    Check the continuity between wire harness and body ground

    OK: 

    No continuity

    1. NG: Repair or replace the wire harness 
    2. OK: Go to next step. 
    Fig 1: Checking Continuity Between Wire Harness & Body Ground
    G01497320Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Check body ECU 

    PREPARATION: 

    Connect the connector of body ECU

    CHECK: 

    Check the DTC

    OK: 

    B1242/42 is not output

    1. NG: Replace the body ECU 
    2. OK: Go to next step. 

    Replace the tuner 

    Fig 2: Connecting Connector Of Body ECU
    G01497321Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002


  1. Check light sensor (See  INSPECTION  ) 
    1. NG: Replace the light sensor 
    2. OK: Go to next step. 
  2. Check wire harness and connector between light sensor and theft deterrent ECU 
    1. NG: Repair or replace wire harness or connector 
    2. OK: Go to next step. 

    Replace the theft deterrent ECU 



  1. Check ECM 

    CHECK: 

    Check that the engine starts normally

    HINT:

    With this inspection ECM CPU can be diagnosed if it works normally or not

    1. NG: replace the ECM 
    2. OK: Go to next step. 
  2. Check wire harness 

    PREPARATION: 

    Disconnect connector or body ECU "E4" of ECM and A12 of A/C ECU

    CHECK: 

    1. Check continuity between terminals MPX1 of body ECU and MPX2 of ECM
    2. Check continuity between terminals MPX1 of ECM and MPX-of A/C ECU

    OK: 

    There is a continuity if wire harness of either (a) or (b) or either (a) or (b)

    HINT:

    If there is OPEN in wire harness of either (a) or (b) please repair it

    1. NG: Repair or replace wire harness 
    2. OK: Go to next step. 

    Replace the ECM 

    Fig 1: Checking Continuity In Wire Harness
    G01497325Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002


  1. Check theft deterrent ECU 

    CHECK: 

    check that the operation of the theft deterrent function is normal

    HINT:

    With this inspection, the theft deterrent ECU CPU can be diagnosed if it works normally or not

    1. NG: Replace the theft deterrent ECU 
    2. OK: Go to next step. 
  2. Check wire harness 

    PREPARATION: 

    Disconnect connector "B6" of body ECU "C9" of combination meter ECU and "T6" of theft deterrent ECU

    CHECK: 

    1. Check continuity between terminals MPX2 of theft deterrent ECU and MPX+ of combinations meter ECU
    2. Check continuity between terminals MPX2 of body ECU and MPX1 of theft deterrent ECU

    OK: 

    There is a continuity if wire harness of both (a) or (b) or either (a) or (b)

    HINT:

    If there is OPEN in wire harness of either (a) or (b) please repair it

    Fig 1: Checking Continuity In Wire Harness
    G01497329Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: Repair or replace wire harness 
    2. OK: Go to next step. 

    Replace the theft deterrent ECU 



  1. Check combination meter ECU 

    CHECK: 

    Start the engine and check that the speed meter and tachometer operate normally

    HINT:

    With this inspection, the combination meter ECU CPU can be diagnosed if it works normally or not

    1. NG: Replace the combination meter ECU 
    2. OK: Go to next step. 
  2. Check wire harness 

    PREPARATION: 

    Disconnect connector "A13" of A/C ECU. "C9" of combination meter ECU and "T6" of theft deterrent ECU.

    CHECK: 

    1. Check continuity between terminals MPX+ of A/C ECU and MPX- of combination meter ECU.
    2. Check continuity between terminals MPX+ of combination meter and MP+2 of theft deterrent ECU.

    OK: 

    There is a continuity in wire harness of both (a) and (b), or either (a) or (b)

    HINT:

    If there is OPEN in wire harness of either (a) or (b), please repair it.

    Fig 1: Checking Continuity In Wire Harness
    G01497331Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: Repair or replace wire harness. 
    2. OK: Go to next step. 

    Replace the combination meter ECU. 

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.