Lexus ES: Communication Malfunction between ECUs Connected by LIN (B2785)
DESCRIPTION
If the certification ECU (smart key ECU assembly) detects a communication error with an ECU connected to the certification bus lines for 7 seconds or more, DTC B2785 will be stored.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area |
|---|---|---|---|
| B2785 | Communication Malfunction between ECUs Connected by LIN |
|
|
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
-
Before performing the inspection, check that DTC B2786 or B278C is not output.
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- When using the Techstream with the power switch off, connect the Techstream to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the Techstream and the vehicle begins. Then select the vehicle type under manual mode and enter the following menus Body Electrical Smart Access. While using the Techstream, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the Techstream and the vehicle.
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Before replacing the certification ECU (smart key ECU assembly), ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator or upper bracket assembly), refer to Registration.
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PROCEDURE
| 1. | CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - EACH ECU) |
(a) Disconnect the G47 certification ECU (smart key ECU assembly) connector.
(b) Disconnect the G51 steering lock ECU (steering lock actuator or upper bracket assembly) connector.
(c) Disconnect the G52 ID code box (immobiliser code ECU) connector.
(d) Measure the resistance according to the value(s) in the table below.
NOTICE:
Make sure that each ECU is in sleep mode before performing the inspection. To enter sleep mode, turn the power switch from on (IG) to off and wait for 180 seconds or more without operating any switches.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| G47-13 (LIN) - G51-5 (LIN) | Power switch off | Below 1 Ω |
| G47-13 (LIN) - G52-2 (LIN1) | Power switch off | Below 1 Ω |
| G47-13 (LIN), G51-5 (LIN) or G52-2 (LIN1) - Body ground | Power switch off | 10 kΩ or higher |
| NG |  | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
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| 2. | CHECK FOR DTC (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)) |
(a) Connect the G47 certification ECU (smart key ECU assembly) connector.
(b) Connect the G52 ID code box (immobiliser code ECU) connector.
(c) Clear the DTCs.
Body Electrical > Smart Access > Clear DTCs(d) Recheck for DTCs.
Body Electrical > Smart Access > Trouble Codes| Result | Proceed to |
|---|---|
| DTC B2785 is output | A |
| DTC B2785 is not output | B |
| B | | REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY) |
|
| 3. | CHECK FOR DTC (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)) |
(a) Connect the G51 steering lock ECU (steering lock actuator or upper bracket assembly) connector.
(b) Disconnect the G52 ID code box (immobiliser code ECU) connector.
(c) Clear the DTCs.
Body Electrical > Smart Access > Clear DTCs(d) Recheck for DTCs.
Body Electrical > Smart Access > Trouble Codes| Result | Proceed to |
|---|---|
| DTC B2785 is output | A |
| DTC B2785 is not output | B |
| A | | REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) |
| B | | REPLACE ID CODE BOX (IMMOBILISER CODE ECU) |
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Diagnostic Trouble Code Chart
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Installation
INSTALLATION CAUTION / NOTICE / HINT HINT:
Use the same procedure for the RH side and LH side.
The following procedure is for the LH side.
PROCEDURE 1. PRECAUTION NOTICE: After turning the engine switch (for Gasoline Model) or power switch (for HV Model) off, waiting time may be required bef
Replacement
REPLACEMENT
CAUTION / NOTICE / HINT
The necessary procedures (adjustment, calibration, initialization or registration)
that must be performed after parts are removed and installed, or replaced during
automatic transaxle fluid replacement are shown below.
Necessary Procedures After Parts Remov
