Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Lost Communication with Front Panel LIN (B14B2)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Gasoline Model) / Lost Communication with Front Panel LIN (B14B2)

DESCRIPTION

The air conditioning control panel (radio and display receiver 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 panel (radio and display receiver assembly) is operated.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B14B2

Lost Communication with Front Panel LIN

Lost communication with air conditioning control assembly
  • Harness or connector
  • Air conditioning control panel (radio and display receiver assembly)
  • Air conditioning amplifier assembly

Memorized

(10 sec. or more)*
  • *: The air conditioning amplifier assembly stores this DTC if the malfunction has occurred for the period of time indicated in the brackets.

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 PANEL (RADIO AND DISPLAY RECEIVER ASSEMBLY) - POWER SOURCE AND BODY GROUND)

(a) Disconnect the G20 air conditioning control panel (radio and display receiver assembly) connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

G20-3 (+B) - Body ground

Engine switch off

11 to 14 V

G20-2 (IG+) - Body ground

Engine switch on (IG)

11 to 14 V

G20-10 (ACC) - Body ground

Engine switch on (ACC)

11 to 14 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

G20-6 (GND) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL PANEL (RADIO AND DISPLAY RECEIVER ASSEMBLY) - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the G35 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

G20-8 (LIN1) - G35-14 (LIN1)

Always

Below 1 Ω

G20-8 (LIN1) or G35-14 (LIN1) - Other terminals and body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Connect the G35 air conditioning amplifier assembly connector.

(b) Turn the engine switch on (IG).

(c) Using an oscilloscope, check the waveform.

Item

Content

Terminal No.

G35-14 (LIN1) - Body ground

Tool Setting

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

Condition

Engine switch on (IG)

OK:

Waveform is similar to that shown in the illustration.

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

OK

4.

INSPECT AIR CONDITIONING CONTROL PANEL (RADIO AND DISPLAY RECEIVER ASSEMBLY)

*a

Component with harness connected

(Air Conditioning Control Panel (Radio and Display Receiver Assembly))

(a) Connect the G20 air conditioning control panel (radio and display receiver assembly) connector.

(b) Turn the engine switch on (IG).

(c) Using an oscilloscope, check the waveform.

Item

Content

Terminal No.

G20-8 (LIN1) - Body ground

Tool Setting

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

Condition

Engine switch on (IG)

OK:

Waveform is similar to that shown in the illustration.

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPLACE AIR CONDITIONING CONTROL PANEL (RADIO & DISPLAY RECEIVER ASSEMBLY)

    Ambient Temperature Display System

    Refrigerant Shortage (B14B8)

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