Toyota Avalon (XX50): Power Source Control ECU Malfunction (B2782). Antenna Coil Open / Short (B2784). IG2 Signal Malfunction (B2788)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Key System(for Start Function, Hv Model) / Power Source Control ECU Malfunction (B2782). Antenna Coil Open / Short (B2784). IG2 Signal Malfunction (B2788)

Power Source Control ECU Malfunction (B2782)

DESCRIPTION

The certification ECU (smart key ECU assembly) has a power source mode switching function.

This DTC is stored when the IGE input (the steering lock motor activation permission signal) sent directly from the certification ECU (smart key ECU assembly) to the steering lock ECU (steering lock actuator or upper bracket assembly) is determined to be abnormal.

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
B2782	Power Source Control ECU Malfunction	Either 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 motor activation command circuit has a short circuit. The steering lock motor activation command circuit has an open circuit. HINT: If the power supply signal from the LIN communication line does not match the power supply signal from the direct line, the system is determined to be malfunctioning.	Steering lock ECU (steering lock actuator or upper bracket assembly) Certification ECU (smart key ECU assembly) Wire harness or connector	DTC Output Confirmation Operation: Perform a steering lock/unlock operation. (The steering locks when a door is opened with the shift lever in P and the power switch off. The steering unlocks when the power switch is turned on (ACC) or on (IG) while carrying the key.)

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2782

Power Source Control ECU Malfunction

Either 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 motor activation command circuit has a short circuit.
The steering lock motor activation command circuit has an open circuit.

HINT:

If the power supply signal from the LIN communication line does not match the power supply signal from the direct line, the system is determined to be malfunctioning.

Steering lock ECU (steering lock actuator or upper bracket assembly)
Certification ECU (smart key ECU assembly)
Wire harness or connector

DTC Output Confirmation Operation:

Perform a steering lock/unlock operation. (The steering locks when a door is opened with the shift lever in P and the power switch off. The steering unlocks when the power switch is turned on (ACC) or on (IG) while carrying the key.)

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
B2782	-

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
When disconnecting the cable from the negative (-) auxiliary battery terminal, some systems need to be initialized after the cable is reconnected.
Click here
Before replacing the steering lock ECU (steering lock actuator or upper bracket assembly) or certification ECU (smart key ECU assembly), refer to Registration.
Click here

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (GROUND)

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G43-1 (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))

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

(a) Connect the G43 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

(b) Move the shift lever to P and turn the power switch off.

Component with harness connected

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

Steering lock motor not operating

Steering lock motor operating

Waveform

OK:

Tester Connection	Condition	Tool Setting	Specified Condition
G43-3 (IGE) - G43-1 (GND)	2 V/DIV., 200 ms./DIV.	Steering lock motor not operating → Operating → Not operating	Pulse generation (See waveform)

Tester Connection

Condition

Tool Setting

Specified Condition

G43-3 (IGE) - G43-1 (GND)

2 V/DIV., 200 ms./DIV.

Steering lock motor not operating → Operating → Not operating

Pulse generation

(See waveform)

HINT:

When taking measurements when the lock motor is stopped, it is not necessary to perform any operations.
In order to take measurements when the lock motor is operating, perform either of the following operations:
- To unlock the steering, carry the electrical key transmitter sub-assembly and turn the power switch on (ACC) or on (IG).
- To lock the steering, turn the power switch off with the shift lever in P, and then open a door.

GO TO STEP 5

3.	CLEAR DTC AND DATA LIST MALFUNCTION RECORD

(a) Clear the DTCs.

Body Electrical > Smart Key > Clear DTCs

(b) Disconnect the cable from the negative (-) auxiliary battery terminal, wait for 30 seconds or more, and then reconnect the cable to the negative (-) auxiliary battery terminal to clear the record of malfunctions stored in the Data List.

CAUTION:

After turning the power switch off, waiting time may be required before disconnecting the cable from the auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the auxiliary battery terminal notices before proceeding with work.

Click here

4.	CHECK FOR DTC

(a) Perform the DTC output confirmation operation.

(b) Check if DTC B2782 is output.

Body Electrical > Smart Key > Trouble Codes

Result	Proceed to
DTC B2782 is not output.	A
DTC B2782 is output.	B

SYSTEM RETURNED TO NORMAL (DTC STORED DUE TO BAD CONNECTION, BUT SYSTEM RETURNED TO NORMAL BY RECONNECTING CONNECTOR)

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

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

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

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

OK:

There is no deformation or corrosion of the connector case or terminals.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G43-3 (IGE) - G40-25 (SLR+)	Always	Below 1 Ω
G43-3 (IGE) or G40-25 (SLR+) - Other terminals and body ground	Always	10 kΩ or higher

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPAIR OR REPLACE HARNESS OR CONNECTOR

Antenna Coil Open / Short (B2784)

DESCRIPTION

When an open or short circuit is detected in the transponder key amplifier coil built into the power switch, the certification ECU (smart key ECU assembly) stores this DTC. This DTC is also stored as a history DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2784	Antenna Coil Open / Short	The transponder key amplifier coil built into the power switch is open (see below) or shorted (determined by communication with certification ECU (smart key ECU assembly)). (1 trip detection logic*)	Power switch Certification ECU (smart key ECU assembly) Wire harness or connector	DTC output confirmation operation: With the shift lever in P and the electrical key transmitter sub-assembly held near the power switch, a hybrid control system start operation is performed by pressing and holding the power switch when the transmitter battery is depleted.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2784

Antenna Coil Open / Short

The transponder key amplifier coil built into the power switch is open (see below) or shorted (determined by communication with certification ECU (smart key ECU assembly)). (1 trip detection logic*)

Power switch
Certification ECU (smart key ECU assembly)
Wire harness or connector

DTC output confirmation operation:

With the shift lever in P and the electrical key transmitter sub-assembly held near the power switch, a hybrid control system start operation is performed by pressing and holding the power switch when the transmitter battery is depleted.

*: 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 cannot be started when transmitter battery is depleted by holding electrical key transmitter sub-assembly near power switch and pressing and holding power switch with shift lever in P	-

Related Data List and Active Test

DTC No.	Data List and Active Test
B2784	-

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
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

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Smart Key > Clear DTCs

2.	CHECK FOR DTC

(a) Perform "DTC Output Confirmation Operation" procedure.

(b) Check for DTCs.

Body Electrical > Smart Key > Trouble Codes

OK:

DTC B2784 is not output.

USE SIMULATION METHOD TO CHECK

3.	CHECK POWER SWITCH (OUTPUT)

(a) Using an oscilloscope, check the waveform.

Component with harness connected

(Power Switch)

Waveform

Waveform (detail)

OK:

Tester Connection	Condition	Tool Setting	Specified Condition
G117-8 (CODE) - G117-6 (AGND)	Power switch off, power switch pressed with electrical key transmitter sub-assembly held near power switch*	1 V/DIV., 20 ms./DIV.	Pulse generation (See waveform)
2 V/DIV., 100 μs./DIV.	Pulse generation (See waveform (detail))

Tester Connection

Condition

Tool Setting

Specified Condition

G117-8 (CODE) - G117-6 (AGND)

Power switch off, power switch pressed with electrical key transmitter sub-assembly held near power switch*

1 V/DIV., 20 ms./DIV.

Pulse generation

(See waveform)

2 V/DIV., 100 μs./DIV.

Pulse generation

(See waveform (detail))

*: Remove the transmitter battery before performing this inspection.

OK:

The waveform is similar to that shown in the illustration.

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPLACE POWER SWITCH

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:

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 power switch is on (IG).))	Steering lock ECU (steering lock actuator or upper bracket assembly) Wire harness or connector	DTC Output Confirmation Operation: No confirmation operation is necessary (monitoring is continuous).

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 power switch is on (IG).))

Steering lock ECU (steering lock actuator or upper bracket assembly)
Wire 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 hybrid control system cannot be started.	-

Related Data List and Active Test Items

DTC No.	Data List and Active Test
B2788	-

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 for circuits related to this system before performing the following procedure.
Before replacing the steering lock ECU (steering lock actuator or upper bracket 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 (POWER SOURCE)

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
G43-6 (IG2) - Body ground	Power switch on (IG)	11 to 14 V
G43-6 (IG2) - Body ground	Power switch off	Below 1 V

*a	Front view of wire harness connector (to Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	CHECK HARNESS AND CONNECTOR (GROUND)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G43-1 (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))

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

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