Toyota Venza manuals

Toyota Venza: Short to GND in Immobiliser System Power Source Circuit (B278A)

Toyota Venza Service Manual / Theft Deterrent / Keyless Entry / Engine Immobiliser System(w/ Smart Key System) / Short to GND in Immobiliser System Power Source Circuit (B278A)

DESCRIPTION

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

DTC No.

DTC Detection Condition

Trouble Area

B278A

Engine switch power source supply line is open or shorted.

  • Wire harness or connector
  • Engine switch
  • Certification ECU (Smart key ECU assembly)

WIRING DIAGRAM


CAUTION / NOTICE / HINT

NOTICE:

If the certification ECU (smart key ECU assembly) is replaced, register the key (See page ).


PROCEDURE

1.

CHECK DTC OUTPUT

(a) Clear the DTCs (See page ).


(b) Recheck for DTCs (See page ).


OK:

DTC B278A is not output.


OK

USE SIMULATION METHOD TO CHECK


NG

2.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH)

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

(b) Disconnect the engine switch connector.


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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D25-28 (VC5) - D13-14 (VC5)

Always

Below 1 Ω

D25-36 (AGND) - D13-8 (AGND)

Always

Below 1 Ω

D25-28 (VC5) - Body ground

Always

10 kΩ or higher

D25-36 (AGND) - 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 Engine Switch)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

3.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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

(b) Reconnect the engine switch connector.

(c) Using an oscilloscope, check the waveform.


Waveform (Reference):

Item

Content

Tester Connection

D25-28 (VC5) - D25-36 (AGND)

Tool Setting

2 V/DIV., 200 ms./DIV.

Condition

  • Engine switch off
  • Key not in cabin
  • Engine switch pressed within 30 seconds

OK:

Waveform is output normally (see illustration)

Result

Proceed to

NG

A

OK (for 2GR-FE)

B

OK (for 1AR-FE)

C

Text in Illustration

*1

Component with harness connected

(Certification ECU (Smart Key ECU Assembly))

*2

GND


A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


B

REPLACE ENGINE SWITCH


C

REPLACE ENGINE SWITCH

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DESCRIPTION This DTC is stored when one of the following occurs: 1) the ECM detects an error in its own communication with the certification ECU (smart key ECU assembly); 2) the ECM detects an er ...

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