DTC B14B3: Lost Communication with Rear Panel LIN [12/2019 - 10/2022]: Procedure

1. Disconnect the T2 No. 2 air conditioning control assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to No. 2 Air Conditioning Control Assembly)

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   T2-7 (E) - Body ground	Always	Below 1 Ω

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   T2-9 (IG) - Body ground	Ignition switch ON	11 to 14 V
   	Ignition 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 H64 air conditioning amplifier assembly connector.
2. Disconnect the T2 No. 2 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
   H64-20 (RLIN) - T2-8 (RLIN)	Always	Below 1 Ω
   H64-20 (RLIN) or T2-8 (RLIN) - 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. Connect the H64 air conditioning amplifier assembly connector.
2. Disconnect the T2 No. 2 air conditioning control assembly connector.
3. Using an oscilloscope, check the waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component with harness connected (Air Conditioning Amplifier Assembly)

   -

   -

   Item	Content
   Tester Connection	H64-20 (RLIN) - Body ground
   Tool Setting	2 V/DIV., 20 μs/DIV.
   Condition	Ignition switch ON

   OK

   The waveform displays properly.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE NO. 2 AIR CONDITIONING CONTROL ASSEMBLY. Refer to  REMOVAL [12/2019 - ] 

Result: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]