B278A

ENGINE IMMOBILISER: ENGINE IMMOBILISER SYSTEM: B278A: Short to GND in Immobiliser System Power Source Circuit

DTC B278A - Short to GND in Immobiliser System Power Source Circuit

DESCRIPTION

This DTC is output when the power switch power source circuit is open or shorted.






WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE: If the certification ECU (smart key ECU assembly) is replaced, register the keys and ECU communication ID. Engine Immobiliser System

PROCEDURE

1. CHECK DTC OUTPUT
(a) Delete the DTCs.
(b) Recheck for DTCs.
OK:
B278A output does not recur.
NG -- CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - POWER SWITCH)
OK -- USE SIMULATION METHOD TO CHECK
2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - POWER SWITCH)





(a) Disconnect the certification ECU (smart key ECU assembly) and power switch connectors.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (POWER SWITCH POWER SOURCE)





(a) Reconnect the certification ECU (smart key ECU assembly) and power switch connectors.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (POWER SWITCH BODY GROUND)





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






NG -- REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)
OK -- REPLACE POWER SWITCH