Toyota CH-R Service Manual: Lost Communication with Front Seat Temperature Adjustment Switch LIN (B14B5)

DESCRIPTION

The seat heater switch (air conditioning control assembly) communicates with the air conditioning amplifier assembly via LIN communication.

If the LIN communication system is malfunctioning, the air conditioning amplifier assembly will not operate even if the seat heater switch (air conditioning control assembly) is operated.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B14B5	Lost Communication with Front Seat Temperature Adjustment Switch LIN	Lost communication with the seat heater switch (air conditioning control assembly)	Seat heater switch (air conditioning control assembly) Air conditioning amplifier assembly Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Air Conditioner > Clear DTCs

NEXT

2.	CHECK FOR DTC

(a) Check for DTCs.

Click here

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B14B5 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.	CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - SEAT HEATER SWITCH (AIR CONDITIONING CONTROL ASSEMBLY) - BODY GROUND)

(a) Disconnect the seat heater switch (air conditioning control assembly) connector.

*a Front view of wire harness connector (to Seat Heater Switch (Air Conditioning Control Assembly))

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
F61-10 (IG+) - Body ground	Ignition switch ON	11 to 14 V
	Ignition switch off	Below 1 V

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F61-16 (GND) - Body ground	Always	Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.	CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - SEAT HEATER SWITCH (AIR CONDITIONING CONTROL ASSEMBLY))

(a) Disconnect the F61 seat heater switch (air conditioning control assembly) connector.

(b) Disconnect the F72*1 or F139*2 air conditioning amplifier assembly connector.

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

Standard Resistance:

for TMMT Made

Tester Connection	Condition	Specified Condition
F61-2 (LIN1) - F72-3 (LIN1)	Always	Below 1 Ω
F61-2 (LIN1) or F72-3 (LIN1) - Body ground	Always	10 kΩ or higher

for TMC Made

Tester Connection	Condition	Specified Condition
F61-2 (LIN1) - F139-14 (LIN1)	Always	Below 1 Ω
F61-2 (LIN1) or F139-14 (LIN1) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.	REPLACE SEAT HEATER SWITCH (AIR CONDITIONING CONTROL ASSEMBLY)

(a) Temporarily replace the seat heater switch (air conditioning control assembly) with a new or known good one.

Click here

NEXT

6.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Air Conditioner > Clear DTCs

OK:

DTC B14B5 is not output.

NEXT

7.	CHECK FOR DTC

(a) Check for DTCs.

Click here

Body Electrical > Air Conditioner > Trouble Codes

OK:

DTC B14B5 is not output.

OK

END (SEAT HEATER SWITCH (AIR CONDITIONING CONTROL ASSEMBLY) WAS DEFECTIVE)

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY