DTC B142A-88: Servo Motor LIN Communication Bus off [08/2023 - ]: Procedure

1. Perform the Active Test according to the display on the GTS.

   Body Electrical > Air Conditioner > Active Test 

   Tester Display	Measurement Item	Control Range	Diagnostic Note
   Front Left Air Mix Damper Control Servo Motor	This test activates the front left air mix damper control servo motor. (No. 1 air conditioning radiator damper servo sub-assembly (front left side air mix))	128: Min 384: Max	Operate with the ignition switch ON.
   Front Right Air Mix Damper Control Servo Motor	This test activates the front right air mix damper control servo motor. (No. 1 air conditioning radiator damper servo sub-assembly (front right side air mix))	128: Min 384: Max	Operate with the ignition switch ON.
   Air Inlet Damper Control Servo Motor	This test activates the air inlet damper control servo motor. (No. 5 air conditioning radiator damper servo sub-assembly)	128: Min 384: Max	Operate with the ignition switch ON.
   Front Air Outlet Damper Control Servo Motor	This test activates the front air outlet damper control servo motor. (No. 1 air conditioning radiator damper servo sub-assembly (front mode))	128: Min 384: Max	Operate with the ignition switch ON.
   Fr Control Rear Air Mix Damper Control Servo Motor	This test activates the front control rear air mix damper control servo motor. (No. 4 air conditioning radiator damper servo sub-assembly (rear air mix))	128: Min 384: Max	Operate with the ignition switch ON.
   Fr Control Rear Air Outlet Damper Servo Motor	This test activates the rear air outlet damper control servo motor. (No. 2 air conditioning radiator damper servo sub-assembly (rear mode))	128: Min 384: Max	Operate with the ignition switch ON.

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Front Left Air Mix Damper Control Servo Motor

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Front Right Air Mix Damper Control Servo Motor

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Air Inlet Damper Control Servo Motor

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Front Air Outlet Damper Control Servo Motor

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Fr Control Rear Air Mix Damper Control Servo Motor

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Fr Control Rear Air Outlet Damper Servo Motor

   Result

   Result	Proceed to
   All of the damper servo motors do not operate	A
   Any of the damper servo motors does not operate	B
   All of the damper servo motors operate	C

Result: 

B 

REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [10/2022 - ] 

Result: 

C 

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

Result: 

A 

See step  2

Pre-procedure1

• Disconnect the z1 air conditioning amplifier assembly connector.

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

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a

  Component without harness connected (Air Conditioning Amplifier Assembly)

  -

  -

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  z1-2 (BUS G) - Body ground	Always	Below 1 Ω	Ω

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

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  z1-4 (B BUS) - z1-2 (BUS G)	Ignition switch off	11 to 14 V	V

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None

Result: 

NG 

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

Result: 

OK 

See step  3

Pre-procedure1

• Disconnect the z1 air conditioning amplifier assembly connector.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a

  Component without harness connected (Air Conditioning Amplifier Assembly)

  -

  -

• Using an oscilloscope, check the waveform.

  Item	Content
  Tester Connection	z1-3 (BUS) - z1-2 (BUS G)
  Tool Setting	2 V/DIV., 20 μs/DIV.
  Condition	Ignition switch ON

  OK

  The waveform displays properly.

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None

Result: 

OK 

REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [10/2022 - ] 

Result: 

NG 

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