Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

Securities. Lexus Gs430, Gs300. Uzs190 Grs190
Engine Immobiliser. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK WIRE HARNESS (CERTIFICATION ECU - ENGINE SWITCH)

CHECK OPERATION OF ENGINE SWITCH

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 short.

DTC No.
DTC Detection Condition
Trouble Area
B278A
Engine switch power source supply line is open or short
  1. Wire harness
  1. Engine switch
  1. Certification ECU

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.Engine Immobiliser.Engine Immobiliser System. Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit


INSPECTION PROCEDURE

1.CHECK WIRE HARNESS (CERTIFICATION ECU - ENGINE SWITCH)

Lexus Gs430, Gs300. Uzs190 Grs190.Engine Immobiliser.Engine Immobiliser System. Dtc B278A Short To Gnd In Immobiliser System Power Source Circuit

  1. Disconnect the V28 and L29 switch connectors.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    V28-30 (VC5) - L29-14 (VC5)
    		Below 1 Ω
    V28-40 (AGND) - L29-8 (AGND)
    		Below 1 Ω
    V28-30 (VC5) or L29-14 (VC5) - Body ground
    		10 kΩ or higher
    V28-40 (AGND) or- L29-8 (AGND) - Body ground
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


2.CHECK OPERATION OF ENGINE SWITCH

  1. After replacing the engine switch with a normal one, check that the engine starts (Click here).

    OK:
    Engine starts.


NG
REPLACE CERTIFICATION ECU
OK

REPLACE ENGINE SWITCH