Multiplex Communication System: Pre-Check

1. The BEAN communication line is used to control the airbag sensor assy center (airbag ECU), the Engine Control Module (ECM), the air conditioner amplifier (A/C ECU), the combination meter assy, the multiplex network door ECU rear RH (power slide door ECU RH), the multiplex network door ECU back (power back door ECU) and the multiplex network door ECU rear LH (power slide door ECU LH). If there is a short-circuit (bus-down) in the line, the communication to the system that has a short-circuit (bus-down) will be disabled and the DTC concerning the system will be output from the multiplex network body ECU.
   Fig 1: Identifying Communication System Diagram

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2. If DTC of ECU communication stop is output, connectors may be disconnected, or communication buses may be open at 2 points. It will not become abnormal with only 1 communication bus open.
   Fig 2: Disconnecting Connector

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3. If 2 communication buses are open at the position as shown in the illustration, DTC of ECU communication stop between those 2 buses is output.
   Fig 3: Identifying Communication System Buses

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1. Check the battery voltage.

   Standard: 10 to 14 V 

2. Inspect the DTC output.
   1. Check a DTC concerning the multiplex network body ECU by connecting the hand-held tester to the DLC3 and turning the ignition switch ON.

      HINT:

      • When DTC check is impossible, check the following items.
      • The display shows communication error (refer to new diagnosis system and the operations when an error occurred).
   2. When the display shows DTCs concerning the ECU unconnected and the communication bus defective, perform the inspection depending on the troubleshooting procedures.

HINT:

When another DTC is output, refer to the DTC table and check the applicable section.

CHECK DTC 

1. Prepare the hand-held tester.
2. Connect the hand-held tester to DLC3.
3. Turn the ignition switch ON and push the hand-held tester main switch ON.
4. Use the hand-held tester to check the DTCs, note them down (For opening instructions, see the hand-held tester's instruction book.).
   Fig 4: Connecting Hand-Held Tester To DLC3

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. See DIAGNOSTIC TROUBLE CODE TABLE  to confirm the details of the DTCs.

1. DTC will be cleared when the malfunction output to DTC is recovered normally.