DTC B1440-88: Rear Servo Motor LIN Communication Bus off [12/2023 - ]: 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
   Rear Air Mix Damper Control Servo Motor	This test activates the rear air mix damper control servo motor. (Rear air mix damper servo sub-assembly)	128: Min 384: Max	Operate with the ignition switch ON.
   Rear Air Outlet Damper Control Servo Motor	This test activates the rear air outlet damper control servo motor. (Rear mode damper servo sub-assembly)	128: Min 384: Max	Operate with the ignition switch ON.

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Rear Air Mix Damper Control Servo Motor

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Rear Air Outlet Damper Control Servo Motor

   OK

   Damper servo motor is operated.

   Result

   Result	Proceed to
   All damper servo motors are not operated	A
   Any damper servo motor is not operated	B
   All damper servo motors are operated	C

Result: 

B 

REPLACE NO. 2 AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [09/2023 - ] 

Result: 

C 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [09/2023 - ] 

Result: 

A 

See step  2

Pre-procedure1

• Disconnect the D36 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
  D36-3 (RBUG) - 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
  D36-2 (RBBU) - D36-3 (RBUG)	Ignition switch off	11 to 14 V

• Using an oscilloscope, check the waveform.

  Item	Content
  Tester Connection	D36-7 (RBUS) - D36-3 (RBUG)
  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: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [09/2023 - ] 

Result: 

OK 

See step  3

Pre-procedure1

• Connect the D36 air conditioning amplifier assembly connector.
• Disconnect the I11 No. 2 air conditioning harness assembly connector.

• 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. 2 Air Conditioning Harness Assembly)

  Standard Resistance

  Tester Connection	Condition	Specified Condition
  I11-2 (RBUG) - 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
  I11-4 (RBBU) - I11-2 (RBUG)	Ignition switch off	11 to 14 V

• Using an oscilloscope, check the waveform.

  Item	Content
  Tester Connection	I11-3 (RBUS) - I11-2 (RBUG)
  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 NO. 2 AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [09/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - NO. 2 AIR CONDITIONING HARNESS ASSEMBLY)