Toyota CH-R Service Manual: Theft Deterrent System Communication Line High Fixation (B279A)

DESCRIPTION

If the communication line (EFIO-IMI) to the transponder key ECU assembly is stuck high (e.g. shorted to +B), the ECM stores this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B279A	Theft Deterrent System Communication Line High Fixation	Communication line (EFIO-IMI) between the ECM and transponder key ECU assembly is stuck high.	Wire harness or connector ECM Transponder key ECU assembly	Turn the ignition switch to ON and wait 6 seconds.

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Operation when Malfunction Detected
Engine cannot be started (initial ignition occurs and engine cranks, then ignition stops)	Engine cannot be started

Related Data List and Active Test

DTC No.	Data List and Active Test
B279A	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Powertrain > Engine and ECT > Clear DTCs

NEXT

2.	CHECK FOR DTC

(a) Check for DTCs.

Powertrain > Engine and ECT > Trouble Codes

HINT:

Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.

OK:

DTC B279A is not output.

Result	Proceed to
B279A is not output	A
B279A is output	B

A

USE SIMULATION METHOD TO CHECK

B

3.	CHECK CONNECTION OF CONNECTOR

(a) Check that the connectors are properly connected to the ECM and transponder key ECU assembly.

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

4.	CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU ASSEMBLY - ECM AND BODY GROUND)

(a) Disconnect the F22 transponder key ECU assembly connector

(b) Disconnect the A38 ECM connector

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F22-13 (EFIO) - A38-28 (IMI)	Always	Below 1 Ω
F22-13 (EFIO) - Body ground	Always	10 kΩ or higher
A38-28 (IMI) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.	REPLACE TRANSPONDER KEY ECU ASSEMBLY

(a) Replace the transponder key ECU assembly with a new one.

Click here

NEXT

6.

CLEAR DTC

(a) Clear the DTCs.

Powertrain > Engine and ECT > Clear DTCs

NEXT

7.	CHECK FOR DTC

(a) Check for DTCs.

Powertrain > Engine and ECT > Trouble Codes

HINT:

Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.

OK:

DTC B279A is not output.

Result	Proceed to
B279A is not output	A
B279A is output	B

A

END (TRANSPONDER KEY ECU ASSEMBLY WAS DEFECTIVE)

B

REPLACE ECM