Toyota Yaris: Lin Communication System / ID-BOX Missing Message (B278987)

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Power Source & Network / Networking / Lin Communication System / ID-BOX Missing Message (B278987)

DESCRIPTION

This DTC is stored when LIN communication between the certification ECU (smart key ECU assembly) and ID code box (immobiliser code ECU) stops for 10 seconds or more.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B278987	ID-BOX Missing Message	No communication between certification ECU (smart key ECU assembly) and ID code box (immobiliser code ECU) for 10 seconds or more.	ID code box (immobiliser code ECU) Certification ECU (smart key ECU assembly) Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.
If the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is replaced, refer to Registration.
When using the GTS with the ignition switch off, connect the GTS to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the GTS and the vehicle begins. Then select Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Entry & Start (CAN). While using the GTS, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the GTS and the vehicle.

PROCEDURE

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Smart Key > Clear DTCs

2.	CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Smart Key > Trouble Codes

Result	Proceed to
DTC B278987 and B278588 are output	A
Only DTC 278987 is output	B
DTC B278987 and B278588 are not output	C

GO TO DTC CHART

USE SIMULATION METHOD TO CHECK

3.	CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - AUXILIARY BATTERY AND BODY GROUND)

(a) Disconnect the H67 ID code box (immobiliser code ECU) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
H67-5 (GND) - Body ground	Always	Below 1 Ω

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
H67-1 (+B) - Body ground	Ignition switch off	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ID CODE BOX (IMMOBILISER CODE ECU))

(a) Disconnect the H46 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the H67 ID code box (immobiliser code ECU) connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
H46-8 (LIN) - H67-2 (LIN1)	Always	Below 1 Ω

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR

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