Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: ACC Monitor Malfunction (B2274)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Access System With Push-button Start (for Start Function) / ACC Monitor Malfunction (B2274)

DESCRIPTION

This DTC is stored when a malfunction in the ACC output circuit is detected. The ACC output circuit is the circuit between terminal ACCD of the certification ECU (smart key ECU assembly) and the ACC relay.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2274

ACC Monitor Malfunction

The ACC relay circuit of the certification ECU (smart key ECU assembly) is malfunctioning. (1-trip detection logic*)

HINT:

When the voltage at terminal ACCD is not at the standard, the system is determined to be malfunctioning.
  • AM2 fuse
  • Instrument panel junction block assembly
  • Certification ECU (Smart key ECU assembly)
  • Wire harness or connector
  • Wait 10 seconds after turning the engine switch on (ACC) or on (IG), and then wait another 10 seconds after turning the engine switch off.
  • *: Only detected while a malfunction is present.
Vehicle Condition and Fail-safe Function when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Function when Malfunction Detected
  • If there is a malfunction due to the ACC relay being stuck on, the ACC relay does not turn off even though the engine switch is off.
  • If there is a malfunction due to the ACC relay being stuck off, the ACC relay does not turn on even though the engine switch is on (ACC).

HINT:

The engine switch can be turned on (IG) and the engine can be started.

-
Related Data List and Active Test Items

DTC No.

Data List and Active Test

B2274
Power Source Control
  • ACC Relay Monitor
Starting Control
  • Ignition

WIRING DIAGRAM

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.
  • The smart access system with push-button start (for Start Function) uses the LIN communication system and CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the smart access system with push-button start (for Start Function) after confirming that the communication systems are functioning properly.

    Click here

  • Inspect the fuses of circuits related to this system before performing the following procedure.
  • Before replacing the certification ECU (smart key ECU assembly), refer to the smart access system with push-button start (for Start Function) Precaution.

    Click here

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

HINT:

When the cable is disconnected and reconnected to the negative (-) battery terminal, the power source mode returns to the state it was in before the cable was disconnected.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (POWER SOURCE)

Click here

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR IN CIRCUIT CONNECTED TO POWER SOURCE
OK

2.

CHECK HARNESS AND CONNECTOR (GROUND)

Click here

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 2A and 2B instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J41-16 (ACCD) - 2A-30

Always

Below 1 Ω

2B-3 - Body ground

Always

Below 1 Ω

J41-16 (ACCD) or 2A-30 - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

CHECK INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (ACC RELAY)

(a) Remove the instrument panel junction block assembly.

Click here

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

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

2A-30 - 2B-3

20°C (68°F)

285.71 to 428.57 Ω

2E-1 - 2A-40

Battery voltage not applied between terminals 2A-30 and 2B-3

10 kΩ or higher

Battery voltage not applied between terminals 2A-30 and 2B-3

Below 1 Ω
NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

OK

5.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Reconnect the J41 certification ECU (smart key ECU assembly) connector.

*a

Component with harness connected

(Certification ECU (Smart Key ECU Assembly))

(b) Install the instrument panel junction block assembly.

Click here

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

J41-16 (ACCD) - Body ground

Engine switch off → Engine switch on (ACC)

1 V or less → 8.5 V or higher
OK

END (TEMPORARY CONNECTION FAILURE IS SUSPECTED)

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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