Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit


DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH)

CHECK CERTIFICATION ECU

DTC B278A Short to GND in Immobiliser System Power Source Circuit


DESCRIPTION

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

DTC Code
DTC Detection Condition
Trouble Area
B278A
The engine switch power source supply line is open or shorted.
  1. Harness or connector
  1. Engine switch
  1. Certification ECU

WIRING DIAGRAM


Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.Theft Deterrent Keyless Entry.Entry And Start System (For Entry Function). Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit


INSPECTION PROCEDURE

NOTICE:
Before replacing the certification ECU, refer to the Service Bulletin.
1.CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH)

  1. Disconnect the G38 ECU connector.

  1. Disconnect the G36 switch connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    G38-28 (VC5) - G36-14 (VC5)
    		Always
    		Below 1 Ω
    G38-36 (AGND) - G36-8 (AGND)
    G38-28 (VC5) or G36-14 (VC5) - Body ground
    		Always
    		10 kΩ or higher
    G38-36 (AGND) or G36-8 (AGND) - Body ground


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.CHECK CERTIFICATION ECU


    Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.Theft Deterrent Keyless Entry.Entry And Start System (For Entry Function). Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

  1. Using an oscilloscope, check the waveform.

    Measurement Condition
    Item
    		Content
    Tester Connection
    		G36-14 (VC5) - G36-8 (AGND)
    Tool Setting
    		2 V/DIV., 20 ms./DIV.
    Condition
    		Engine switch off, key not in cabin, and 30 seconds or less after engine switch pushed
    OK:
    Waveform is output normally (refer to illustration).
    Text in Illustration
    *a
    		Component with harness connected
    (Engine Switch)
    HINT:
    If replacing the Engine Switch, refer to the procedures below.
    1. for 1GR-FE (for LHD LandCruiser RM000002YWC047X.html)
    2. for 1GR-FE (for RHD LandCruiser RM000002YWC048X.html
    3. for 2TR-FE LandCruiser RM000002YWC046X.html)
    4. for 1KD-FTV (for LHD LandCruiser RM000002YWC049X.html)
    5. for 1KD-FTV (for RHD LandCruiser RM000002YWC04AX.html)
    6. for 1GD-FTV (for LHD LandCruiser RM000002YWC04BX.html)
    7. for 1GD-FTV (for RHD LandCruiser RM000002YWC04CX.html)


NG
REPLACE CERTIFICATION ECU
OK

REPLACE ENGINE SWITCH