DTC B142A-88: Servo Motor LIN Communication Bus off [11/2021 - ]: Procedure
WARNING: This page is about a different car, the 2025 Lexus NX 350h, 2024 Lexus NX 350h, 2023 Lexus NX 350h, and 2022 Lexus NX 350h. However, it is still accessible from the selected car via links, so may be relevant.
- CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY NOTE:
When inspecting the air conditioning amplifier assembly, be careful not to cause a short.
- Disconnect the z21 air conditioning amplifier assembly connector.
*a Component without harness connected
(Air Conditioning Amplifier Assembly)- - - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition z21-2 (BUS G) - Body ground Always Below 1 Ω - Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition z21-4 (B BUS) - z21-2 (BUS G) Ignition switch off 11 to 14 V - Using an oscilloscope, check the waveform.
Item Content Tester Connection z21-3 (BUS) - z21-2 (BUS G) Tool Setting 2 V/DIV., 20 μs/DIV. Condition Ignition switch ON OK
The waveform displays properly.
Result
Proceed to OK NG
Result:
NG
REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to REMOVAL [11/2021 - ]
Result:
OK
See step 2
- Disconnect the z21 air conditioning amplifier assembly connector.
- CHECK AIR CONDITIONING HARNESS ASSEMBLY
- Disconnect the z21 air conditioning amplifier assembly connector.
- Disconnect the A No. 1 air conditioning radiator damper servo sub-assembly connector.
- Measure the resistance according to the value(s) in the table below.
*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 Air Conditioning Amplifier Assembly)Standard Resistance
Tester Connection Condition Specified Condition z21-2 (BUS G) - A-6 (BUS G) Always Below 1 Ω z21-3 (BUS) - A-7 (BUS) Always Below 1 Ω z21-4 (B BUS) - A-8 (B BUS) Always Below 1 Ω Result
Proceed to OK NG
Result:
OK
REPLACE NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY. Refer to DISASSEMBLY [11/2021 - 03/2024] , or refer to DISASSEMBLY [03/2024 - ]
Result:
NG
REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to DISASSEMBLY [11/2021 - 03/2024] , or refer to DISASSEMBLY [03/2024 - ]