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 output when the engine 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 the key Engine Immobilizer System.

PROCEDURE

1. CHECK DTC OUTPUT

(a) Clear the DTCs Engine Immobilizer System.

(b) Recheck for DTCs.

OK:

B278A output does not recur.

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

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

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

(a) Disconnect the certification ECU (smart key ECU assembly) and engine 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 (ENGINE SWITCH POWER SOURCE)

(a) Reconnect the certification ECU (smart key ECU assembly) and engine switch connectors.





(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





NG -- REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Removal
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (ENGINE 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) Removal

OK -- REPLACE ENGINE SWITCH Removal