DTC B14B2: Lost Communication with Front Panel LIN [11/2018 - 02/2019]: Procedure

1. Disconnect the air conditioning control assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Air Conditioning Control Assembly)

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G24-13 (GND) - Body ground	Always	Below 1 Ω

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   G24-9 (IG+) - Body ground	Power switch on (IG)	11 to 14 V
   	Power switch off	Below 1 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  2

1. Disconnect the G24 air conditioning amplifier assembly connector.
2. Disconnect the G46 air conditioning control assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G24-7 (LIN1) - G46-7 (LIN1)	Always	Below 1 Ω
   G24-7 (LIN1) or G46-7 (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

1. Using an oscilloscope, check the waveform.

   Item	Content
   Tester Connection	G46-7 (LIN1) - Body ground
   Tool Setting	2 V/DIV., 20 μs/DIV.
   Condition	Power switch on (IG)

   OK

   The waveform displays properly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Air Conditioning Amplifier Assembly)

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [11/2018 - ] 

Result: 

NG 

REPLACE AIR CONDITIONING CONTROL ASSEMBLY. Refer to  REMOVAL [11/2018 - ]