Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

Vehicle Interior. Corolla. Zre142 Aze141
Theft Deterrent Keyless Entry. Corolla. Zre142 Aze141

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK DTC OUTPUT

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH)

CHECK HARNESS AND CONNECTOR (ENGINE SWITCH POWER SOURCE)

CHECK HARNESS AND CONNECTOR (ENGINE SWITCH BODY GROUND)

DTC B278A Short to GND in Immobiliser System Power Source Circuit


DESCRIPTION

This DTC is output when the engine switch power source supply line is open or shorted.

DTC No.
DTC Detection Condition
Trouble Area
B278A
Engine switch power source supply line is open or shorted
  1. Wire harness or connector
  2. Engine switch
  3. Certification ECU (smart key ECU assembly)

WIRING DIAGRAM


Corolla. Zre142 Aze141.Theft Deterrent Keyless Entry.Smart Key System (For Entry Function). Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit


INSPECTION PROCEDURE

NOTICE:
If the certification ECU (smart key ECU assembly) is replaced, register the key and ECU communication ID (COROLLA_ZRE142 RM000000QYF05AX.html).
1.CHECK DTC OUTPUT

  1. Clear the DTCs (COROLLA_ZRE142 RM000001GV807OX.html).

  1. Recheck for DTCs.

    OK:
    B278A is not reoutput.


NG
Go to step 2
OK

USE SIMULATION METHOD TO CHECK (COROLLA_ZRE142 RM000000UZ108OX.html)

2.CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH)

  1. Disconnect the certification ECU (smart key ECU assembly) connector.



    Corolla. Zre142 Aze141.Theft Deterrent Keyless Entry.Smart Key System (For Entry Function). Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

  1. Disconnect the engine switch connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    E36-30 (VC5) - E38-14 (VC5)
    		Always
    		Below 1 Ω
    E36-40 (AGND) - E38-8 (AGND)
    		Always
    		Below 1 Ω
    E36-17 (E) - Body ground
    		Always
    		Below 1 Ω
    E36-30 (VC5) - Body ground
    		Always
    		10 kΩ or higher
    E36-40 (AGND) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.CHECK HARNESS AND CONNECTOR (ENGINE SWITCH POWER SOURCE)

  1. Reconnect the certification ECU (smart key ECU assembly) connector.



    Corolla. Zre142 Aze141.Theft Deterrent Keyless Entry.Smart Key System (For Entry Function). Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

  1. Reconnect the engine switch connector.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    E36-30 (VC5) - Body ground
    		Key is not in cabin
    		Below 1 V
    E36-30 (VC5) - Body ground
    		Engine switch pressed
    		4.6 to 5.4 V


NG
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (COROLLA_ZRE142 RM000003G0O004X.html)
OK


4.CHECK HARNESS AND CONNECTOR (ENGINE SWITCH BODY GROUND)


    Corolla. Zre142 Aze141.Theft Deterrent Keyless Entry.Smart Key System (For Entry Function). Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    E36-40 (AGND) - Body ground
    		Always
    		Below 1 Ω


NG
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (COROLLA_ZRE142 RM000003G0O004X.html)
OK

REPLACE ENGINE SWITCH (COROLLA_ZRE142 RM000002YWC033X.html)