Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Engine Starter Communication Malfunction (B2779)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System / Engine Starter Communication Malfunction (B2779)

DESCRIPTION

If the remote engine start ECU does not respond to the certification ECU (smart key ECU assembly) or the remote engine start ID is not registered, this DTC is stored.

HINT:

Registration status of the remote engine start ECU ID can be checked using the "Wireless C Code" item in the Data List.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2779

Engine Starter Communication Malfunction

One of the following conditions is met (1 trip detection logic*):

  • A remote start communication error occurs.
  • Response is not possible.
  • Registration has not been performed.
  • Remote engine start ECU
  • Main body ECU (multiplex network body ECU)
  • Certification ECU (smart key ECU assembly)

DTC output confirmation operation:

  • A remote start operation is performed.

*: Only output while a malfunction is present.

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Operation when Malfunction Detected

Engine does not start with remote start operation

Engine cannot be started by remote start operation only
Related Data List and Active Test

DTC No.

Data List and Active Test

B2779
  • Wireless Starter Com ID
  • Wireless C Code

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the engine 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.
  • Before performing the inspection, check that DTC B1242 (wireless door lock control) is not output.
  • Before replacing the certification ECU (smart key ECU assembly) or main body ECU (multiplex network body ECU), refer to Registration.

    Click here

  • After performing repairs, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.

CHECK CAN COMMUNICATION SYSTEM

(a) Check for CAN communication system DTCs.

Click here

OK:

CAN communication DTCs are not output.

NG

GO TO CAN COMMUNICATION SYSTEM (DIAGNOSTIC TROUBLE CODE CHART)

OK

2.

READ VALUE USING TECHSTREAM (WIRELESS C CODE)

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Smart Access / Data List.

(f) Read the Data List according to the display on the Techstream.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Wireless C Code

Registration status between remote engine starter ECU and certification ECU (smart key ECU assembly)

No Regd or Regd

No Regd: Remote starter ID not registered to remote engine start ECU and certification ECU (smart key ECU assembly)

Regd: Remote starter ID registered Remote starter ID remote engine start ECU and certification ECU (smart key ECU assembly)

Problems may be caused by the following:

  • DTC B2779 is stored.
  • Remote engine start ECU registration has not been performed.
  • Malfunctions in the certification ECU (smart key ECU assembly) or remote engine start ECU.
Body Electrical > Smart Access > Data List

Tester Display

Wireless C Code

Result

Proceed to

"No Regd" is displayed on the Techstream

A

"Regd" is displayed on the Techstream

B
B

GO TO STEP 5

A

3.

REGISTER REMOTE ENGINE STARTER ID

(a) Register the remote engine starter ID.

NEXT

4.

CHECK REMOTE ENGINE STARTER FUNCTION

(a) Check the remote engine starter function.

OK:

Remote engine starter functions operate normally.

OK

END (REMOTE ENGINE STARTER ID WAS NOT REGISTERED)
NG

GO TO STEP 5

5.

REPLACE REMOTE ENGINE STARTER ECU

(a) Temporarily replace the remote engine starter ECU with a new one.

HINT:

Register the remote engine starter ID.

(b) Check the remote engine starter function.

OK:

Remote engine starter functions operate normally.

OK

END (REMOTE ENGINE STARTER ECU WAS DEFECTIVE)
NG

6.

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

(a) Temporarily replace the main body ECU (multiplex network body ECU) with a new one.

Click here

(b) Check the remote engine starter function.

OK:

Remote engine starter functions operate normally.

OK

END (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) WAS DEFECTIVE)
NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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