DTC B2278: Engine/Power Switch Malfunction [10/2018 - 07/2022]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine 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
   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.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  3

Result: 

OK 

See step  2

1. Enter the following menus: Body Electrical / Power Source Control / Data List.
2. 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.

   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.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2018 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

1. Disconnect the F44 certification ECU (smart key ECU assembly) connector.
2. Disconnect the F47 engine switch connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F44-23 (SSW1) - F47-5 (SS1)	Always	Below 1 Ω
   F44-21 (SSW2) - F47-1 (SS2)	Always	Below 1 Ω
   F44-11 (AGND) - F47-6 (AGND)	Always	Below 1 Ω
   F44-23 (SSW1) or F47-5 (SS1) - Other terminals and body ground	Always	10 kΩ or higher
   F44-21 (SSW2) or F47-1 (SS2) - Other terminals and body ground	Always	10 kΩ or higher
   F44-11 (AGND) or F47-6 (AGND) - Other terminals and body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Remove the engine switch.

   Refer to REMOVAL [10/2018 - 07/2022]

2. Inspect the engine switch.

   Refer to INSPECTION [10/2018 - 07/2022]

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [10/2018 - 07/2022] 

Result: 

NG 

REPLACE ENGINE SWITCH. Refer to  REMOVAL [10/2018 - 07/2022]