DTC B2284: Brake Signal Malfunction [12/2021 - ]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Power Source Control / Data List.
5. 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
   Stop Light Switch1	State of brake pedal	OFF or ON	OFF: Brake pedal released ON: Brake pedal depressed	Use this item to determine if the stop light switch assembly is malfunctioning. The hybrid control system cannot be started when this item is OFF. If the stop light switch assembly is malfunctioning, the hybrid control system can be started by pressing and holding the power switch for a certain period of time.

   Body Electrical > Power Source Control > Data List 

   Tester Display
   Stop Light Switch1

   OK

   The Techstream display changes correctly in response to the brake pedal operation.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING). Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2021 - ] 

Result: 

NG 

See step  2

1. Disconnect the M7 certification ECU (smart key ECU assembly) connector.
2. Disconnect the A29 hybrid vehicle control ECU assembly connector.
3. Disconnect the A105 No. 2 skid control ECU (brake actuator assembly) connector.
4. Disconnect the A40 stop light switch assembly connector.
5. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   M7-25 (STP1) - A40-3 (L)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Reconnect the certification ECU (smart Key ECU assembly) connector.
2. Reconnect the A40 stop light switch assembly connector.
3. Measure the voltage according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   M7-25 (STP1) - Body ground	Brake pedal released → depressed	1 V or less → 9 V or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [12/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023]  , or refer to  REMOVAL [10/2023 - ] 

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [11/2018 - ]