Toyota Avalon (XX50): Steering Lock Position Signal Circuit Malfunction (B2285). Engine Starter Communication Malfunction (B2779). Open / Short in Steering Lock ECU (B2781)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Key System(for Start Function, Hv Model) / Steering Lock Position Signal Circuit Malfunction (B2285). Engine Starter Communication Malfunction (B2779). Open / Short in Steering Lock ECU (B2781)

Steering Lock Position Signal Circuit Malfunction (B2285)

DESCRIPTION

This DTC is stored when the steering lock position signal sent by the steering lock ECU (steering lock actuator or upper bracket assembly) via direct line and the steering lock position signal sent via LIN communication do not match.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2285	Steering Lock Position Signal Circuit Malfunction	The steering lock position signal sent by the steering lock ECU (steering lock actuator or upper bracket assembly) via direct line and the steering lock position signal sent via LIN communication do not match. (1-trip detection logic*1)	LIN communication system Steering lock ECU (steering lock actuator or upper bracket assembly) Certification ECU (smart key ECU assembly) Wire harness or connector DCM (telematics transceiver)*2	Disconnect the cable from the negative (-) auxiliary battery terminal, wait 30 seconds and then reconnect the cable to the negative (-) auxiliary battery terminal. Wait at least 40 seconds with the power switch off (wait is the steering locked), then turn the power switch on (IG) (steering unlocked) and wait at least 40 seconds.

*1: Only detected while a malfunction is present and the power switch is on (IG).
*2: for Toyota Entune Remote Connect Compatible Type

Vehicle Condition and Fail-safe Function when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Function when Malfunction Detected
The hybrid control system cannot be started.	The ECU does not send a hybrid control system start request.

Related Data List and Active Test Items

DTC No.	Data List and Active Test
B2285	Power Source Control Steering Unlock Switch Smart Key Power Supply Short Motor Driver Short Lock Bar Stuck Error

DTC No.

Data List and Active Test

B2285

Power Source Control

Steering Unlock Switch

Smart Key

Power Supply Short
Motor Driver Short
Lock Bar Stuck Error

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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 Key. 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 key system (for Start Function, HV Model) uses the LIN communication system and CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the smart key system (for Start Function, HV Model) 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), steering lock ECU (steering lock actuator or upper bracket assembly) or DCM (telematics transceiver)*, refer to Registration.
Click here
- *: for Toyota Entune Remote Connect Compatible Type
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.	CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Smart Key > Trouble Codes

HINT:

If the steering cannot be unlocked, the power switch cannot be turned on (IG) and the hybrid control system cannot be started.
If LIN communication is not available, the steering cannot be locked or unlocked.

OK:

LIN communication system DTC B2785 is not output simultaneously.

GO TO DTC B2785

2.	READ VALUE USING TECHSTREAM (STEERING UNLOCK SWITCH)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Body Electrical / Power Source Control / Data List.

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

Body Electrical > Power Source Control > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Steering Unlock Switch	State of steering unlock sensor signal output from steering lock ECU (steering lock actuator or upper bracket assembly)	OFF or ON	OFF: Steering locked ON: Steering unlocked	When the shift lever is in P and the power switch is off, if any door is opened or closed, the steering is locked. When the electrical key transmitter sub-assembly is in the cabin and the power switch is turned on (ACC) or on (IG), the steering unlocks. The hybrid control system cannot be started when the steering unlock signal is off.

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Steering Unlock Switch

State of steering unlock sensor signal output from steering lock ECU (steering lock actuator or upper bracket assembly)

OFF or ON

OFF: Steering locked

ON: Steering unlocked

When the shift lever is in P and the power switch is off, if any door is opened or closed, the steering is locked.
When the electrical key transmitter sub-assembly is in the cabin and the power switch is turned on (ACC) or on (IG), the steering unlocks.
The hybrid control system cannot be started when the steering unlock signal is off.

Body Electrical > Power Source Control > Data List

Tester Display
Steering Unlock Switch

OK:

The Techstream display changes.

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

3.	CHECK STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G43-4 (SLP1) - Body ground

Positive (+) tester probe → G43-4 (SLP1)

Negative (-) tester probe → Body ground

Steering locked → unlocked*

10 kΩ or higher → Below 1 Ω

HINT:

*: If any of the doors are opened with the shift lever in P and the power switch off, the steering will be locked. If the power switch is turned on (ACC) or on (IG) with the electrical key transmitter sub-assembly in the cabin, the steering will be unlocked.
DTC B2285 may be stored due to a malfunction in the steering lock ECU (steering lock actuator or upper bracket assembly). The steering lock position signal and unlock position signal are sent from the steering lock ECU (steering lock actuator or upper bracket assembly) to the certification ECU (smart key ECU assembly) individually.

*a	Component with harness connected (Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))

Result	Proceed to
OK (except Toyota Entune Remote Connect Compatible Type)	A
OK (for Toyota Entune Remote Connect Compatible Type)	B
NG	C

GO TO STEP 5

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

4.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY))

(a) Disconnect the G40 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the G43 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G40-14 (SLP) - G43-4 (SLP1)	Always	Below 1 Ω
G40-14 (SLP) or G43-4 (SLP1) - Other terminals and body ground	Always	10 kΩ or higher

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY) - DCM)

(a) Disconnect the G40 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the G43 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G40-14 (SLP) - G43-4 (SLP1)	Always	Below 1 Ω
G43-4 (SLP1) - G9-29 (SLPD)	Always	Below 1 Ω
G40-14 (SLP), G43-4 (SLP1) or G9-29 (SLPD) - Other terminals and body ground	Always	10 kΩ or higher

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
G40-14 (SLP), G43-4 (SLP1) or G9-29 (SLPD) - Body ground	Always	Below 1 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Check the push-button start function.

(1) Enter the vehicle while carrying an electrical key transmitter sub-assembly.

(2) Depress the brake pedal with the shift lever in P.

(3) Check that the hybrid control system starts when the power switch is pressed.

Result	Proceed to
Hybrid control system starts	A
Hybrid control system does not start	B

REPLACE DCM (TELEMATICS TRANSCEIVER)

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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.	CAN communication system Remote engine start ECU Certification ECU (smart key ECU assembly)	DTC output confirmation operation: A remote start operation is performed.

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.

CAN communication system
Remote engine start 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
Hybrid control system does not start with remote start operation	Hybrid control system cannot be started by remote start operation only

Related Data List and Active Test

DTC No.	Data List and Active Test
B2779	Smart Key Wireless Starter Com ID Wireless C Code

CAUTION / NOTICE / HINT

NOTICE:

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 Key. 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 system) is not output.
Before replacing the certification ECU (smart key ECU assembly), 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.

GO TO CAN COMMUNICATION SYSTEM (DIAGNOSTIC TROUBLE CODE CHART)

2.	READ VALUE USING TECHSTREAM (WIRELESS C CODE)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Body Electrical / Smart Key / Data List.

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

Body Electrical > Smart Key > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Wireless C Code	Registration status between remote engine start 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 to 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.

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Wireless C Code

Registration status between remote engine start 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 to 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 Key > 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

REPLACE REMOTE ENGINE START ECU

3.	REGISTER REMOTE ENGINE STARTER ID

(a) Register the remote engine starter ID.

4.	READ VALUE USING TECHSTREAM (WIRELESS C CODE)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Body Electrical / Smart Key / Data List.

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

Body Electrical > Smart Key > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Wireless C Code

Registration status between remote engine start 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 to 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 Key > 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

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPLACE REMOTE ENGINE START ECU

Open / Short in Steering Lock ECU (B2781)

DESCRIPTION

The steering lock ECU and steering lock motor are built into the steering lock actuator or upper bracket assembly.

The steering lock ECU (steering lock actuator or upper bracket assembly) detects whether the steering lock is in the lock or unlock position by using the lock sensor and unlock sensor of the steering lock motor.

The steering lock ECU (steering lock actuator or upper bracket assembly) receives lock and unlock request signals from the certification ECU (smart key ECU assembly) and responds with lock and unlock operation signals.

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

B2781

Open / Short in Steering Lock ECU

One of the following conditions is met (1-trip detection logic (Only output while a malfunction is present and the power switch is on (IG).)):

The steering lock sensor or unlock sensor is malfunctioning (When both detection switches turn on, the system is determined to be malfunctioning).
The steering lock motor activation circuit has a short circuit.
The steering lock motor activation circuit has an open circuit.

Steering lock ECU (steering lock actuator or upper bracket assembly)
LIN communication system

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 hybrid control system cannot be started.	Prohibits the hybrid control system from being started (the hybrid control system does not start).

Related Data List and Active Test Items

DTC No.	Data List and Active Test
B2781	Smart Key Sensor Value Motor Driver Short

CAUTION / NOTICE / HINT

NOTICE:

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 Key. 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 key system (for Start Function, HV Model) uses the LIN communication system and CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the smart key system (for Start Function, HV Model) after confirming that the communication systems are functioning properly.
Click here
Before replacing the steering lock ECU (steering lock actuator or upper bracket assembly), refer to Registration.
Click here
After performing repairs, confirm that no DTCs are output again.
Click here

HINT:

When all the ECUs that are connected via LIN communication cannot communicate with the certification ECU (smart key ECU assembly), DTC B2785 is stored.

PROCEDURE

CHECK DTC

(a) Using the Techstream, check if LIN communication DTC B2785 is output.

Body Electrical > Smart Key > Trouble Codes

HINT:

If a LIN communication DTC is output, perform troubleshooting for the LIN communication system.

Click here

Result	Proceed to
DTC B2785 is output.	A
DTC B2785 is not output.	B

GO TO LIN COMMUNICATION SYSTEM (DTC B2785)

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

Engine/Power Switch Malfunction (B2278). Vehicle Speed Signal Malfunction (B2282,B2283). Brake Signal Malfunction (B2284)

Power Source Control ECU Malfunction (B2782). Antenna Coil Open / Short (B2784). IG2 Signal Malfunction (B2788)

See More:

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