Toyota Corolla Cross: Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message (B143A87)

Toyota Corolla Cross (2022-2024) Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System (for Hev Model) / Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message (B143A87)

DESCRIPTION

The air conditioning harness assembly and No. 1 air conditioning radiator damper servo sub-assembly connect the air conditioning amplifier assembly and the No. 1 blower damper servo sub-assembly. The air conditioning amplifier assembly supplies power and sends operation instructions to No. 1 blower damper servo sub-assembly through the air conditioning harness assembly and No. 1 air conditioning radiator damper servo sub-assembly. The No. 1 blower damper servo sub-assembly sends pulse signals to inform the air conditioning amplifier assembly of the damper position.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Memory
B143A87	Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message	Diagnosis Condition: Ignition switch ON Malfunction Status: Error or lost communication with No. 1 blower damper servo sub-assembly Detection Time: Continuously for 10 seconds or more	No. 1 blower damper servo sub-assembly Air conditioning harness assembly	Memorized

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B143A87

Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message

Diagnosis Condition:

Ignition switch ON

Malfunction Status:

Error or lost communication with No. 1 blower damper servo sub-assembly

Detection Time:

Continuously for 10 seconds or more

No. 1 blower damper servo sub-assembly
Air conditioning harness assembly

Memorized

DTC Detection Condition Combination Table

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	Ignition switch ON	○	○
Malfunction	Error communication with No. 1 blower damper servo sub-assembly	○	-
Malfunction	Lost communication with No. 1 blower damper servo sub-assembly	-	○
Detection Time		Continuously for 10 seconds or more	Continuously for 10 seconds or more
Trip Count		1 trip	1 trip

HINT:

If the conditions of either of these patterns are detected, a DTC will be stored.

WIRING DIAGRAM

for Dual Type

for Single Type

PROCEDURE

1.	CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result	Proceed to
B142A88 is output	A
B142A88 is not output	B

GO TO DTC B142A88

2.	INSPECT AIR CONDITIONING HARNESS ASSEMBLY

(a) Disconnect the A No. 1 air conditioning radiator damper servo sub-assembly connector.

(b) Disconnect the B No. 1 blower damper servo sub-assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A-1 (M-) - B-5 (M-)	Always	Below 1 Ω
A-2 (M+) - B-4 (M+)	Always	Below 1 Ω
A-3 (STE2) - B-3 (STE2)	Always	Below 1 Ω
A-4 (STE1) - B-2 (STE1)	Always	Below 1 Ω
A-5 (GND) - B-1 (GND)	Always	Below 1 Ω
A-1 (M-) or B-5 (M-) - Other terminals and body ground	Always	10 kΩ or higher
A-2 (M+) or B-4 (M+) - Other terminals and body ground	Always	10 kΩ or higher
A-3 (STE2) or B-3 (STE2) - Other terminals and body ground	Always	10 kΩ or higher
A-4 (STE1) or B-2 (STE1) - Other terminals and body ground	Always	10 kΩ or higher

REPLACE NO. 1 BLOWER DAMPER SERVO SUB-ASSEMBLY

REPLACE AIR CONDITIONING HARNESS ASSEMBLY

SEE MORE:

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Toyota Corolla Cross: Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message (B143A87)

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