DTC B142A-88: Servo Motor LIN Communication Bus off [11/2023 - ]: 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. 1 blower 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.

   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

   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 [11/2023 - ]

Result: 

A 

See step  2

Pre-procedure1

1. Disconnect the z18 air conditioning amplifier assembly connector.

   Procedure1

2. 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
   z18-2 (BUS G) - 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
   z18-4 (B BUS) - z18-2 (BUS G)	Ignition switch off	11 to 14 V

   Result

   Proceed to
   OK
   NG

   Post-procedure1

4. None

Result: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 

Refer to REMOVAL [11/2023 - ]

Result: 

OK 

See step  3

Pre-procedure1

1. Disconnect the z18 air conditioning amplifier assembly connector.

   Procedure1

2. Using an oscilloscope, check the waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Air Conditioning Amplifier Assembly)

   -

   -

   Item	Content
   Tester Connection	z18-3 (BUS) - z18-2 (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

3. None

Result: 

OK 

REPLACE AIR CONDITIONING HARNESS ASSEMBLY 

Refer to DISASSEMBLY [10/2022 - ]

Result: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 

Refer to REMOVAL [11/2023 - ]