B278C

NETWORKING: LIN COMMUNICATION SYSTEM: B278C: Lost Communication with Power Source Control
B278C - Lost Communication with Power Source Control

DESCRIPTION

This DTC is stored when LIN communication between the certification ECU (smart key ECU assembly) and power management control ECU stops for 10 seconds or more.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
* Inspect the fuses for circuits related to this system before performing the following inspection procedure.
* If the certification ECU (smart key ECU assembly) is replaced, register the key Engine Immobilizer System.
* When using the Techstream to troubleshoot with the power switch off:
Connect the Techstream to the DLC3, and turn the courtesy switch on and off at 1.5-second intervals until communication between the Techstream and vehicle begins.

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - BATTERY AND BODY GROUND)

(a) Disconnect the H3 and H4 power management control ECU connectors.

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

Standard Resistance:





Standard Voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

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

(a) Disconnect the H1 certification ECU (smart key ECU assembly) connector.

(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. REPLACE POWER MANAGEMENT CONTROL ECU

(a) Replace the power management control ECU Removal.

NEXT -- Continue to next step.

4. CHECK DTC OUTPUT

(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(b) Recheck for DTCs.

OK:

DTC B278C is not output.

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

OK -- END (POWER MANAGEMENT CONTROL ECU WAS DEFECTIVE)