Toyota Avalon (XX50): ACC Monitor Malfunction (B2274). Detecting Vehicle Submersion (B2277). Engine/Power Switch Malfunction (B2278)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Key System(for Start Function, Gasoline Model) / ACC Monitor Malfunction (B2274). Detecting Vehicle Submersion (B2277). Engine/Power Switch Malfunction (B2278)

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.	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.

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.

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.	-

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

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 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, Gasoline 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, Gasoline 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), refer to Registration.
Click here
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY), BATTERY AND BODY GROUND)

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

(b) Disconnect the 4A, 4D and 4K instrument panel junction block assembly connectors.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G40-16 (ACCD) - 4A-30	Always	Below 1 Ω
4D-3 - Body ground	Always	Below 1 Ω
G40-16 (ACCD) or 4A-30 - Other terminals and body ground	Always	10 kΩ or higher

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
4K-1 - Body ground	Always	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	CHECK INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (ACC RELAY)

(a) Remove the instrument panel junction block assembly.

Click here

(b) Connect all of the instrument panel junction block assembly connectors.

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

Component with harness connected

(Instrument Panel Junction Block Assembly)

Standard Voltage:

Tester Connection	Condition	Specified Condition
4H-26 - Body ground	Engine switch on (ACC)	11 to 14 V

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

3.	CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
G40-16 (ACCD) - Body ground	Engine switch off → Engine switch on (ACC)	1 V or less → 8.5 V or higher

*a	Component with harness connected (Certification ECU (Smart Key ECU Assembly))

END (TEMPORARY CONNECTION FAILURE IS SUSPECTED)

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

Detecting Vehicle Submersion (B2277)

DESCRIPTION

This DTC is stored when a malfunction in the water submersion detection circuit inside the certification ECU (smart key ECU assembly) is detected.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2277	Detecting Vehicle Submersion	Water submersion detected by the water submersion detection circuit inside the certification ECU (smart key ECU assembly). (1-trip detection logic*)	Certification ECU (smart key ECU assembly)	Wait 300 seconds after connecting the cable to the negative (-) battery terminal.

*: 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
The engine switch cannot be turned off and the engine cannot be started.	-

Related Data List and Active Test Items

DTC No.	Data List and Active Test
B2277	-

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 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, Gasoline 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, Gasoline Model) after confirming that the communication systems are functioning properly.
Click here
Before replacing the certification ECU (smart key ECU assembly), refer to Registration.
Click here
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

HINT:

Before proceeding with troubleshooting, check if there are any signs of water damage to the certification ECU (smart key ECU assembly). If there are any signs of water damage, replace the certification ECU (smart key ECU assembly) and take measures against the cause of the water damage.

PROCEDURE

1.	CHECK WATER INTRUSION

(a) Check that the certification ECU (smart key ECU assembly), its ground area and wire harnesses have no signs of water intrusion.

Result	Proceed to
No sign of water intrusion found	A
Signs of water intrusion found	B

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

TAKE MEASURES AGAINST WATER INTRUSION AND REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

Engine/Power Switch Malfunction (B2278)

DESCRIPTION

This DTC is stored when the SSW1 contact signal and SSW2 contact signal, which are detected when the engine switch is operated, do not match.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2278	Engine/Power Switch Malfunction	When the engine switch is operated, the SSW1 contact signal and SSW2 contact signal do not match (1-trip detection logic*).	Engine switch Certification ECU (smart key ECU assembly) Wire harness or connector	Turn the engine switch on (IG).

*: 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 either the SSW1 contact signal or SSW2 contact signal is stuck on, the power source mode cannot be changed by pressing the engine switch. If either the SSW1 contact signal or SSW2 contact signal is stuck off, emergency stop by pressing and holding the engine switch for 2 seconds or more cannot be operated.	-

Related Data List and Active Test Items

DTC No.	Data List and Active Test
B2278	Power Source Control Start Switch1 Start Switch2

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 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, Gasoline 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, Gasoline Model) after confirming that the communication systems are functioning properly.
Click here
Before replacing the certification ECU (smart key ECU assembly), refer to Registration.
Click here
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.	READ VALUE USING TECHSTREAM (START SWITCH1, START SWITCH2)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine 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
Start Switch1	Engine switch 1 status	OFF or ON	OFF: Engine switch not pressed ON: Engine switch pressed	If the engine switch is pressed for a short time, the display may not change. Use this item to determine if the engine switch input signal is malfunctioning.
Start Switch2	Engine switch 2 status	OFF or ON	OFF: Engine switch not pressed ON: Engine switch pressed	Backup for engine switch 1. However, when the engine switch is pressed and held, the control functions only when both engine switch 1 and 2 are normal. Behaves the same way as engine switch 1.

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Start Switch1

Engine switch 1 status

OFF or ON

OFF: Engine switch not pressed

ON: Engine switch pressed

If the engine switch is pressed for a short time, the display may not change.
Use this item to determine if the engine switch input signal is malfunctioning.

Start Switch2

Engine switch 2 status

OFF or ON

OFF: Engine switch not pressed

ON: Engine switch pressed

Backup for engine switch 1. However, when the engine switch is pressed and held, the control functions only when both engine switch 1 and 2 are normal.
Behaves the same way as engine switch 1.

Body Electrical > Power Source Control > Data List

Tester Display
Start Switch1
Start Switch2

OK:

The Techstream display changes correctly in response to the engine switch operation.

GO TO STEP 3

2.	READ VALUE USING TECHSTREAM (START SWITCH1, START SWITCH2)

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

(b) According to the display on the Techstream, read the Data List while wiggling the wire harness.

Body Electrical > Power Source Control > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Start Switch1	Engine switch 1 status	OFF or ON	OFF: Engine switch not pressed ON: Engine switch pressed	If the engine switch is pressed for a short time, the display may not change. Use this item to determine if the engine switch input signal is malfunctioning.
Start Switch2	Engine switch 2 status	OFF or ON	OFF: Engine switch not pressed ON: Engine switch pressed	Backup for engine switch 1. However, when the engine switch is pressed and held, the control functions only when both engine switch 1 and 2 are normal. Behaves the same way as engine switch 1.

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Start Switch1

Engine switch 1 status

OFF or ON

OFF: Engine switch not pressed

ON: Engine switch pressed

If the engine switch is pressed for a short time, the display may not change.
Use this item to determine if the engine switch input signal is malfunctioning.

Start Switch2

Engine switch 2 status

OFF or ON

OFF: Engine switch not pressed

ON: Engine switch pressed

Backup for engine switch 1. However, when the engine switch is pressed and held, the control functions only when both engine switch 1 and 2 are normal.
Behaves the same way as engine switch 1.

Body Electrical > Power Source Control > Data List

Tester Display
Start Switch1
Start Switch2

OK:

The Techstream display changes correctly in response to the engine switch operation.

USE SIMULATION METHOD TO CHECK

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ENGINE SWITCH)

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

(b) Disconnect the G41 engine switch connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G40-23 (SSW1) - G41-5 (SS1)	Always	Below 1 Ω
G40-21 (SSW2) - G41-1 (SS2)	Always	Below 1 Ω
G40-11 (AGND) - G41-6 (AGND)	Always	Below 1 Ω
G40-23 (SSW1) or G41-5 (SS1) - Other terminals and body ground	Always	10 kΩ or higher
G40-21 (SSW2) or G41-1 (SS2) - Other terminals and body ground	Always	10 kΩ or higher
G40-11 (AGND) or G41-6 (AGND) - Other terminals and body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	INSPECT ENGINE SWITCH

(a) Remove the engine switch.

Click here

(b) Inspect the engine switch.

Click here

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPLACE ENGINE SWITCH

Engine Immobiliser System Circuit Short to Battery (B279A12). Engine Immobiliser System Incorrect Assembly (B279C95). Ignition Hold Monitor Malfunction (B2271)

Vehicle Speed Signal Malfunction (B2282,B2283). Brake Signal Malfunction (B2284). Steering Lock Position Signal Circuit Malfunction (B2285)

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