DTC B2278: Engine Switch Circuit Malfunction: Procedure

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

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Start Switch1	Start Switch 1/ON or OFF	ON: Engine switch on (IG) OFF: Engine switch off	-
   Start Switch2	Start Switch 2/ON or OFF	ON: Engine switch on (IG) OFF: Engine switch off	-

   OK

   ON appears on the screen.

NG → See step   3 

OK: Go to next step 

1. Ensure the key is inside the cabin.
2. Check that the power source mode changes as shown below each time the engine switch is pushed.

   OK

   off → on (ACC) → on (IG) → off

NG → See step   6 

OK → SYSTEM IS OK 

Fig 1: Identifying Connector Terminals Of Engine Switch

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the engine switch. Refer to REMOVAL .
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 Connector Terminals Of L36 Engine Switch And L13 Main Body ECU

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard resistance

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

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE MAIN BODY ECU