DTC B143A-87: Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message [11/2021 - ]: Procedure

1. Check for DTCs.

   Body Electrical > Air Conditioner > Trouble Codes 

   Result

   Result	Proceed to
   DTC B142A-88 is output	A
   DTC B142A-88 is not output	B

Result: 

A 

GO TO DTC B142A-88. Refer to  DTC B142A-88: Servo Motor LIN Communication Bus off [11/2021 - ]  

Result: 

B 

See step  2

1. Disconnect the A No. 1 air conditioning radiator damper servo sub-assembly connector.
2. Disconnect the B No. 3 air conditioning radiator damper servo sub-assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Front view of wire harness connector (to No. 1 Air Conditioning Radiator Damper Servo Sub-assembly)

   *b

   Front view of wire harness connector (to No. 3 Air Conditioning Radiator Damper Servo Sub-assembly)

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A-1 (M-) - B-5 (M-)	Always	Below 1 Ω
   A-2 (M+) - B-4 (M+)	Always	Below 1 Ω
   A-3 (STE2) - B-3 (STE2)	Always	Below 1 Ω
   A-4 (STE1) - B-2 (STE1)	Always	Below 1 Ω
   A-5 (GND) - B-1 (GND)	Always	Below 1 Ω
   A-1 (M-) or B-5 (M-) - Other terminals and body ground	Always	10 kΩ or higher
   A-2 (M+) or B-4 (M+) - Other terminals and body ground	Always	10 kΩ or higher
   A-3 (STE2) or B-3 (STE2) - Other terminals and body ground	Always	10 kΩ or higher
   A-4 (STE1) or B-2 (STE1) - Other terminals and body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY. Refer to  DISASSEMBLY [11/2021 - ] 

Result: 

NG 

REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [11/2021 - 03/2024]  , or refer to  DISASSEMBLY [03/2024 - ]