DTC B2278: Engine Switch Circuit Malfunction: 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.

   HINT: 

   When using the Techstream with the engine switch off, turn on and off any of the door courtesy light switches repeatedly at 1.5 second intervals or less until communication between the Techstream and vehicle starts.

   POWER SOURCE CONTROL
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Start Switch1	Start Switch 1 / ON or OFF	ON: Engine switch is pushed OFF: Engine switch is not pushed	-
   Start Switch2	Start Switch 2 / ON or OFF	ON: Engine switch is pushed OFF: Engine switch is not pushed	-

   OK

   ON (engine switch is pushed) and OFF (engine switch is not pushed) appear on the screen according to vehicle operating conditions.

NG → See step   3 

OK: Go to next step 

1. Clear the DTC. Refer to DTC CHECK / CLEAR .
2. Turn the engine switch on (IG).
3. Check for DTCs.
   RESULT
   
   

   Result	Proceed to
   DTC B2278 is not output.	A
   DTC B2278 is output.	B

B → See step   6 

A → See step   5 

1. Remove the engine switch (for 2GR-FSE: Refer to REMOVAL , for 4GR-FSE: Refer to REMOVAL ).
   Fig 1: Engine Switch Connector Terminal Identification

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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

   TEXT IN ILLUSTRATION
   
   

   *1

   Component without harness connected (Engine Switch)

   -

   -

   HINT: 

   This engine switch is momentary type switch.

   RESULT
   
   

   Result	Proceed to
   OK	A
   NG (for 2GR-FSE)	B
   NG (for 4GR-FSE)	C

B → See step   7 

C → See step   9 

A: Go to next step 

1. Disconnect the J55 connector from the power source control ECU.
   Fig 2: J31 And J55 Connector Terminal Identification

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.
   STANDARD RESISTANCE
   
   

   Tester Connection	Condition	Specified Condition
   J31-7 (SS1) - J55-14 (SSW1)	Always	Below 1 Ω
   J31-2 (SS2) - J55-37 (SSW2)	Always	Below 1 Ω
   J31-5 (GND) - Body ground	Always	Below 1 Ω
   J31-7 (SS1) or J55-14 (SSW1) - Body ground	Always	10 kΩ or higher
   J31-2 (SS2) or J55-37 (SSW2) - Body ground	Always	10 kΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Engine Switch)
   *2	Front view of wire harness connector (to Power Source Control ECU)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - ENGINE SWITCH) 

OK → See step   8