Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: IG2 Signal Malfunction (B2788)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Suspension / Steering Column / Steering Lock System / IG2 Signal Malfunction (B2788)

DESCRIPTION

This DTC is stored when the steering lock ECU (steering lock actuator or upper bracket assembly) detects an IG2 power supply malfunction.

HINT:

The steering lock ECU (steering lock actuator or upper bracket assembly) is not connected to the CAN communication system. However, the steering lock ECU (steering lock actuator or upper bracket assembly) is connected to the certification ECU (smart key ECU assembly) via LIN communication and communicates with other components via CAN communication through the certification ECU (smart key ECU assembly).

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2788

IG2 Signal Malfunction

Mismatch between the steering lock ECU (steering lock actuator or upper bracket assembly) IG2 input from the LIN communication system and from the direct line. (1-trip detection logic (Only output while a malfunction is present and the engine switch is on (IG).))
  • IGN NO. 2 fuse
  • Steering lock ECU (Steering lock actuator or upper bracket assembly)
  • Harness or connector

DTC Output Confirmation Operation: No confirmation operation is necessary (monitoring is continuous).
Vehicle Condition and Fail-safe Function when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Function when Malfunction Detected

The steering cannot be locked or unlocked. For this reason, the engine cannot be started.

-
Related Data List and Active Test Items

DTC No.

Data List Item

Active Test Item

B2788

-

-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the engine switch off, connect the Techstream to the vehicle 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 Model Code "KEY REGIST" 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.
  • The steering lock system uses LIN communication. First perform the inspections in "How to Proceed with Troubleshooting" to confirm that there are no communication malfunctions before proceeding with troubleshooting.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • After performing repairs, confirm that no DTCs are output again.

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  • When replacing the steering lock ECU (steering lock actuator or upper bracket assembly), registration must be performed.

    Click here

PROCEDURE

1.

INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.

(b) Disconnect the L1 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

L1-1 (GND) - Body ground

Always

Below 1 Ω

*a

Front view of wire harness connector

(to Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))

(d) Reconnect the L1 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

L1-6 (IG2) - L1-1 (GND)

Engine switch on (IG)

11 to 14 V

L1-6 (IG2) - L1-1 (GND)

Engine switch off

Below 1 V

*a

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))
OK

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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