DTC B2785: Communication Malfunction between ECUs Connected by LIN: Procedure

Fig 1: Identifying Certification ECU And Steering Lock ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the E84 and E77 ECU connectors.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   E84-10 (LIN) - E77-5 (LIN)	Always	Below 1 Ω
   E84-10 (LIN) - Body ground	Always	10 kΩ or higher

3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   E84-10 (LIN) - Body ground	Always	Below 1 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Clear the DTC. Refer to DTC CHECK / CLEAR .
2. Reconnect the E84 ECU connector.
3. Recheck for DTCs.

   OK

   B2785 does not reoccur.

NG → See step   5 

OK: Go to next step 

1. Clear the DTC. Refer to DTC CHECK / CLEAR .
2. Reconnect the E77 ECU connector.
3. Disconnect the 1D ECU connector.
4. Recheck for DTCs.

   OK

   B2785 does not reoccur.

NG → See step   7 

OK: Go to next step 

1. Clear the DTC. Refer to DTC CHECK / CLEAR .
2. Reconnect the 1D ECU connector.
3. Disconnect the E79 ECU connector.
4. Recheck for DTCs.

   OK

   B2785 does not reoccur.

NG → See step   9 

OK → See step   11 

1. Temporarily replace the steering lock ECU with a new one. Refer to REMOVAL .
   NOTE:

   When replacing the steering lock ECU, registration must be performed according to the "Registration" procedures. Refer to REGISTRATION .

2. Clear the DTC. Refer to DTC CHECK / CLEAR .

NEXT: Go to next step 

1. Recheck for DTCs.

   OK

   B2785 does not reoccur.

NG → See step   11 

OK → END (STEERING LOCK ECU IS DEFECTIVE) 

1. Temporarily replace the main body ECU (instrument panel junction block) with a new or normally functioning one.
2. Clear the DTC. Refer to DTC CHECK / CLEAR .

NEXT: Go to next step 

1. Recheck for DTCs.

   OK

   B2785 does not reoccur.

NG → See step   11 

OK → END (MAIN BODY ECU IS DEFECTIVE) 

1. Temporarily replace the ID code box with a new one. Refer to REMOVAL .
   NOTE:

   When replacing the ID code box, registration must be performed according to the "Registration" procedures. Refer to REGISTRATION .

2. Clear the DTC. Refer to DTC CHECK / CLEAR .

NEXT: Go to next step 

1. Recheck for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   B2785 does not reoccur.

NG → See step   11 

OK → END (ID CODE BOX IS DEFECTIVE)