Last Modified: 08-21-2023 6.11:8.1.0 Doc ID: RM100000001A3P5
Model Year Start: 2019 Model: Avalon HV Prod Date Range: [04/2018 - 08/2020]
Title: HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for HV Model): B1279; Lost Communication with Humidity/Rain Sensor LIN; 2019 - 2020 MY Avalon HV [04/2018 - 08/2020]

DTC

B1279

Lost Communication with Humidity/Rain Sensor LIN

DESCRIPTION

The main body ECU (multiplex network body ECU) and air conditioning thermistor assembly communicate via LIN communication.

The main body ECU (multiplex network body ECU) stores this DTC if communication becomes abnormal.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B1279

Lost Communication with Humidity/Rain Sensor LIN

Lost communication with air conditioning thermistor assembly
  • Harness or connector
  • Main body ECU (multiplex network body ECU)
  • Air conditioning thermistor 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:

Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

Click here 2019 - 2020 MY Avalon HV [04/2018 - 08/2020]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): REGISTRATION

HINT:

The air conditioning thermistor assembly must be replaced if the glass temperature sensor is malfunctioning.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING THERMISTOR ASSEMBLY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

(a) Disconnect the G32 main body ECU (multiplex network body ECU) connector.

(b) Disconnect the O4 air conditioning thermistor assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

O4-3 (MPX) - G32-3 (LIN3)

Always

Below 1 Ω

O4-3 (MPX) or G32-3 (LIN3) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

INSPECT MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

*a

Component without harness connected

(Main Body ECU (Multiplex Network Body ECU))

(a) Using an oscilloscope, check the waveform.

OK:

Tester Connection

Condition

Specified Condition

G32-3 (LIN3) -Body ground

Power switch on (IG)

Pulse generation
OK

REPLACE AIR CONDITIONING THERMISTOR ASSEMBLY

NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)