DTC B14B5: Lost Communication with Front Seat Temperature Adjustment Switch LIN [10/2018 - 07/2022]: Procedure

1. Check for DTCs.

   Refer to DTC CHECK / CLEAR [10/2018 - ]

   Body Electrical > Air Conditioner > Trouble Codes 

   OK

   DTC B14B5 is not output.

   Result

   	Proceed to
   Only DTC B14B5 is output	A
   DTC B14B2, B14B5 and B14B7 are output (for Gasoline Model)	B
   DTC B14B2, B14B5 and B14B7 are output (for HV Model)	C

Result: 

B 

GO TO AIR CONDITIONING SYSTEM (B14B2). Refer to  DTC B14B2: Lost Communication with Front Panel LIN [10/2018 - 07/2022] 

Result: 

C 

GO TO AIR CONDITIONING SYSTEM (B14B2). Refer to  DTC B14B2: Lost Communication with Front Panel LIN [10/2018 - 07/2022] 

Result: 

A 

See step  2

1. Disconnect the refreshing seat switch connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Refreshing Seat Switch)

2. Measure the voltage and resistance according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   F38-1 (IG) - Body ground	Ignition switch ON	11 to 14 V
   	Ignition switch off	Below 1 V

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F38-4 (E) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Disconnect the F51 air conditioning amplifier assembly connector.
2. Disconnect the F38 refreshing seat switch connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F51-14 (LIN1) - F38-2 (CN2+)	Always	Below 1 Ω
   F51-14 (LIN1) or F38-2 (CN2+) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Connect the air conditioning amplifier assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Refreshing Seat Switch)

2. Turn the ignition switch to ON.
3. Using an oscilloscope, check the waveform.

   Item	Content
   Terminal No.	F51-14 (LIN1) - Body ground
   Tool Setting	2 V/DIV., 20 ms./DIV.
   Condition	Ignition switch ON

   OK

   Waveform is similar to that shown in the illustration.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

Result: 

OK 

See step  5

1. Connect the refreshing seat switch connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Refreshing Seat Switch)

2. Turn the ignition switch to ON.
3. Using an oscilloscope, check the waveform.

   Item	Content
   Terminal No.	F38-2 (CN2+) - Body ground
   Tool Setting	2 V/DIV., 20 ms./DIV.
   Condition	Ignition switch ON

   OK

   Waveform is similar to that shown in the illustration.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [10/2018 - 07/2022] 

Result: 

NG 

REPLACE REFRESHING SEAT SWITCH. Refer to  REMOVAL [10/2018 - 07/2022]