Toyota Venza manuals

Toyota Venza: Lost Communication with Power Source Control (B278C)

Toyota Venza Service Manual / Networking / Lin Communication System / Lost Communication with Power Source Control (B278C)

DESCRIPTION

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

DTC Code

DTC Detection Condition

Trouble Area

B278C

No communication between the certification ECU (smart key ECU assembly) and power management control ECU for more than 10 seconds.

  • Power management control ECU
  • Certification ECU (Smart key ECU assembly)
  • Wire harness or connector
  • AM2 fuse

WIRING DIAGRAM


CAUTION / NOTICE / HINT

NOTICE:

  • If the certification ECU (smart key ECU assembly) is replaced, register the key.
  • When using the Techstream to troubleshoot with the ignition 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 D43 ECU connector.


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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D43-5 (GND2) - Body ground

Always

Below 1 Ω

D43-6 (GND) - Body ground

Always

Below 1 Ω

Standard Voltage:

Tester Connection

Condition

Specified Condition

D43-1 (AM22) - Body ground

Always

11 to 14 V

D43-2 (AM21) - Body ground

Always

11 to 14 V

Text in Illustration

*1

Power Management Control ECU


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

2.

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

(a) Disconnect the D25 ECU connector.


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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D25-29 (LIN) - D43-24 (LIN2)

Always

Below 1 Ω

D25-29 (LIN) - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Front view of wire harness connector

(to Certification ECU (Smart Key ECU Assembly))

*2

Front view of wire harness connector

(to Power Management Control ECU)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

3.

REPLACE POWER MANAGEMENT CONTROL ECU

(a) Replace the power management control ECU (See page ).



NEXT

4.

CHECK DTC OUTPUT

(a) Clear the DTC (See page ).


(b) Recheck for DTCs.

OK:

DTC B278C is not output.


OK

END (POWER MANAGEMENT CONTROL ECU WAS DEFECTIVE)


NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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