DTC B14B2: Lost Communication with Front Panel LIN [01/2019 - 09/2022]: Procedure

1. Disconnect the I37 air conditioning control assembly connector.
2. Measure the voltage and resistance according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   I37-9 (IG+) - Body ground	Power switch on (IG)	11 to 14 V

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   I37-13 (GND) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  2

1. Disconnect the I49 air conditioning amplifier assembly connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   I37-7 (LIN1) - I49-7 (LIN1)	Always	Below 1 Ω
   I37-7 (LIN1) or I49-7 (LIN1) - Other terminals and body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Connect the I49 air conditioning amplifier assembly connector.
2. Turn the power switch on (IG).
3. Using an oscilloscope, check the waveform.

   OK

   Waveform is similar to that shown in the illustration.

   Item	Content
   Terminal No.	I49-7 (LIN1) - Body ground
   Tool Setting	2 V/DIV., 20 ms./DIV.
   Condition	Power switch on (IG)

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE AIR CONDITIONING CONTROL ASSEMBLY. Refer to  REMOVAL [06/2018 - 09/2024] 

Result: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [01/2019 - 09/2022]