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

DESCRIPTION

If the communication line (IMI - EFIO) between the ECM and ID code box (immobiliser code ECU) is stuck high, the ECM will store this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B279A	Theft Deterrent System Communication Line High Fixation	The communication line (IMI - EFIO) between the ECM and ID code box (immobiliser code ECU) is stuck high. (1 trip detection logic*)	ID code box (immobiliser code ECU) ECM Wire harness or connector	DTC output confirmation operation: Turn the engine switch on (IG) 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	Engine cannot be started

Related Data List and Active Test

DTC No.	Data List and Active Test
B279A	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

When DTC B279A and a certification ECU (smart key ECU assembly) DTC are output simultaneously, first perform troubleshooting for the certification ECU (smart key ECU assembly) DTC.

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Powertrain > Engine and ECT > Clear DTCs

NEXT

2.	CHECK FOR DTC

(a) Turn the engine switch on (IG) and wait 10 seconds.

(b) Check for DTCs.

Click here

Powertrain > Engine and ECT > Trouble Codes

HINT:

If DTCs other than DTC B279A are output, troubleshoot those DTCs first.

Result	Proceed to
Only DTC or B279A is output	A
DTC or B279A and other DTCs are output	B

B

GO TO DIAGNOSTIC TROUBLE CODE CHART

A

3.	CHECK CONNECTION OF CONNECTOR

(a) Turn the engine switch off.

(b) Check that the connectors are properly connected to the ECM and ID code box (immobiliser code ECU).

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

4.	CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - ECM)

(a) Disconnect the F21 ID code box (immobiliser code ECU) 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
F21-4 (EFIO) - A38-28 (IMI)	Always	Below 1 Ω
F21-4 (EFIO) or A38-28 (IMI) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.	REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

(a) Replace the ID code box (immobiliser code ECU) with a new one.

Click here

NEXT

6.	REGISTER RECOGNITION CODE

(a) Register the recognition codes in the ECUs.

Click here

NEXT

7.	REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID.

Click here

NEXT

8.	CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts.

OK:

Engine starts normally.

NG

REPLACE ECM

OK

9.

CLEAR DTC

(a) Clear the DTCs.

Click here

Powertrain > Engine and ECT > Clear DTCs

NEXT

10.	CHECK FOR DTC

(a) Perform "DTC Output Confirmation Operation" procedure.

(b) Check for DTCs.

Click here

Powertrain > Engine and ECT > Trouble Codes

OK:

DTC B279A is not output.

OK

END (ID CODE BOX (IMMOBILISER CODE ECU) WAS DEFECTIVE)

NG

REPLACE ECM