B278A

THEFT DETERRENT / KEYLESS ENTRY: ENGINE IMMOBILISER SYSTEM: B278A: Short to GND in Immobiliser System Power Source Circuit
B278A - Short to GND in Immobiliser System Power Source Circuit

DESCRIPTION

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





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
If the certification ECU (smart key ECU assembly) is replaced, register all the keys Engine Immobilizer System.

PROCEDURE

1. CHECK DTC OUTPUT

(a) Clear the DTCs Engine Immobilizer System.

(b) Recheck for DTCs Engine Immobilizer System.

OK:

DTC B278A is not output.

NG -- CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - POWER SWITCH)

OK -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

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

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

(b) Disconnect the power switch connector.

(c) 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 CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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

(b) Reconnect the power switch connector.

(c) Using an oscilloscope, check the waveform.





Waveform (Reference):





OK:

Waveform is output normally (see illustration)

Text in Illustration





NG -- REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Removal

OK -- REPLACE POWER SWITCH Removal