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 supply line is open or shorted.






WIRING DIAGRAM





INSPECTION PROCEDURE
NOTICE: If the certification ECU is replaced, register the key and ECU communication ID Programming and Relearning.

PROCEDURE

1. CHECK DTC OUTPUT
(a) Delete the DTCs Reading and Clearing Diagnostic Trouble Codes.
(b) Recheck for DTCs Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- USE SIMULATION METHOD TO CHECK
A -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - POWER SWITCH)




(a) Disconnect the E58 ECU and E52 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 E58 ECU and E52 switch connectors.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPLACE CERTIFICATION ECU
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
OK -- REPLACE POWER SWITCH