DTC B2278: Power Switch Circuit Malfunction: Procedure

1. Use the Data List to check if the power switch is functioning properly.
   MAIN BODY
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Start Switch 1	Start Switch 1/ON or OFF	ON: Power switch ON (IG) OFF: Power switch OFF	-
   Start Switch 2	Start Switch 2/ON or OFF	ON: Power switch ON (IG) OFF: Power switch OFF	-

   OK

   When the power switch is turned ON (IG), ON is displayed on the Techstream screen.

NG → See step   3 

OK: Go to next step 

1. Ensure the key is inside the cabin.
2. With the brake pedal released, check that the power source mode changes as shown below each time the power switch is pushed.

   OK

   OFF → ON (ACC) → ON (IG) → OFF

NG → See step   7 

OK → See step   6 

Fig 1: Identifying Power Switch Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the L36 power switch connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   7 (SS1) - 5 (GND)	Pushed	Below 1 Ω
   2 (SS2) - 5 (GND)	Pushed	Below 1 Ω
   7 (SS1) - 5 (GND)	Not pushed	10 kΩ or higher
   2 (SS2) - 5 (GND)	Not pushed	10 kΩ or higher

NG → See step   5 

OK: Go to next step 

Fig 2: Identifying Main Body ECU And Power Switch Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the L13 main body ECU connector.
2. Disconnect the L36 power switch connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   L13-17 (SSW1) - L36-7 (SS1)	Always	Below 1 Ω
   L13-16 (SSW2) - L36-2 (SS2)	Always	Below 1 Ω
   L36-5 (GND) - Body ground	Always	Below 1 Ω
   L13-17 (SSW1) or L36-7 (SS1) - Body ground	Always	10 kΩ or higher
   L13-16 (SSW2) or L36-2 (SS2) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE MAIN BODY ECU