Toyota Yaris: Air Conditioning System / Lost Communication with Front Panel LIN Missing Message (B14B287)

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / Lost Communication with Front Panel LIN Missing Message (B14B287)

DESCRIPTION

The air conditioning control assembly communicates with the air conditioning amplifier assembly via LIN communication.

If a malfunction occurs in the LIN communication system, the air conditioning amplifier assembly will not operate, even if the air conditioning control assembly is operated.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B14B287

Lost Communication with Front Panel LIN Missing Message

Diagnosis Condition:

  • Ignition switch ON

Malfunction Status:

  • Error or lost communication with air conditioning control assembly

Detection Time:

  • Continuously for 10 seconds or more
  • Air conditioning control assembly
  • Harness or connector
  • Air conditioning amplifier assembly

Memorized
DTC Detection Condition Combination Table
 

Vehicle Condition

Pattern 1

Pattern 2

Diagnosis Condition

Ignition switch ON

○

○

Malfunction

Error communication with air conditioning control assembly

○

-

Lost communication with air conditioning control assembly

-

○

Detection Time

Continuously for 10 seconds or more

Continuously for 10 seconds or more

Trip Count

1 trip

1 trip

HINT:

If the conditions of either of these patterns are detected, a DTC will be stored.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - IG POWER SOURCE)

(a) Disconnect the air conditioning control assembly connector.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

H31-9 (IG+) - Body ground

Ignition switch ON

10.5 to 16 V

*a

Front view of wire harness connector

(to Air Conditioning Control Assembly)
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - BODY GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

H31-13 (GND) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the H24 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

H31-7 (LIN1) - H24-7 (LIN1)

Always

Below 1 Ω

H31-7 (LIN1) or H24-7 (LIN1) - Other terminals and body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Connect the H24 air conditioning amplifier assembly connector.

(b) Using an oscilloscope, check the waveform.

Item

Content

Terminal No.

H24-7 (LIN1) - Body ground

Tool Setting

2 V/DIV., 20 ms./DIV.

Condition

Ignition switch ON

OK:

Waveform is similar to that shown in the illustration.
NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

OK

5.

INSPECT AIR CONDITIONING CONTROL ASSEMBLY

(a) Connect the air conditioning control assembly connector.

*a

Component with harness connected

(Air Conditioning Control Assembly)

(b) Using an oscilloscope, check the waveform.

Item

Content

Terminal No.

H31-7 (LIN1) - Body ground

Tool Setting

2 V/DIV., 20 ms./DIV.

Condition

Ignition switch ON

OK:

Waveform is similar to that shown in the illustration.

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPLACE AIR CONDITIONING CONTROL ASSEMBLY

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