DTC B2278: Engine Switch Circuit Malfunction: Procedure

WARNING: This page is about a different car, the 2012 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.

READ VALUE USING TECHSTREAM (START SWITCH)

Connect the Techstream to the DLC3.

Check the Data List for proper functioning of the start switch.

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.

MAIN BODY

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Start Switch 1	Start Switch 1 / ON or OFF	ON: Engine switch is pushed OFF: Engine switch is not pushed	-
Start Switch 22	Start Switch 2 / ON or OFF	ON: Engine switch is pushed OFF: Engine switch is not pushed	-

ON (engine switch is pushed) and OFF (engine switch is not pushed) appear on the screen.

NG → See step 2

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)

INSPECT ENGINE SWITCH

Remove the engine switch. Refer to REMOVAL .

Fig 1: Inspecting Engine Switch
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the switch connector.

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

HINT:

This switch is a momentary type switch.

NG → See step 4

OK: Go to next step

CHECK HARNESS AND CONNECTOR (ENGINE SWITCH - MAIN BODY ECU AND BODY GROUND)

Disconnect the E51 ECU connector.

Fig 2: Identifying E51 ECU And E38 Switch Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the E38 switch connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
E38-7 (SS1) - E51-10 (SSW1)	Always	Below 1 Ω
E38-2 (SS2) - E51-9 (SSW2)	Always	Below 1 Ω
E38-5 (GND) - Body ground	Always	Below 1 Ω
E38-7 (SS1) or E51-10 (SSW1) - Body ground	Always	10 kΩ or higher
E38-2 (SS2) or E51-9 (SSW2) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE SWITCH - MAIN BODY ECU AND BODY GROUND)

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)

REPLACE ENGINE SWITCH. Refer to REMOVAL