Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: BUS IC Communication Malfunction (B1497/97)

Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / BUS IC Communication Malfunction (B1497/97)

DESCRIPTION

Front Air Conditioning System

The air conditioning harness assembly connects the air conditioning amplifier assembly and the servo motors. The air conditioning amplifier assembly supplies power and sends operation instructions to each servo motor through the air conditioning harness assembly. Each servo motor sends damper position information to the air conditioning amplifier assembly.

Rear Air Conditioning System (w/ Rear Air Conditioning System)

The No. 2 air conditioning harness assembly connects the air conditioning amplifier assembly and the servo motors. The air conditioning amplifier assembly supplies power and sends operation instructions to each servo motor through the No. 2 air conditioning harness assembly. Each servo motor sends damper position information to the air conditioning amplifier assembly.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B1497/97

BUS IC Communication Malfunction

Error or open in communication line
  • Air conditioning harness assembly
  • No. 1 air conditioning radiator damper servo sub-assembly
  • No. 2 air conditioning radiator damper servo sub-assembly
  • No. 3 air conditioning radiator damper servo sub-assembly
  • No. 1 blower damper servo sub-assembly
  • Air conditioning amplifier assembly
  • No. 2 air conditioning harness assembly*2
  • Rear No. 1 cooling unit damper servo sub-assembly*2
  • Rear No. 2 cooling unit damper servo sub-assembly*2

Memorized

(10 sec. or more)*1
  • *1: The air conditioning amplifier assembly stores this DTC if the malfunction has occurred for the period of time indicated in the brackets.
  • *2: w/ Rear Air Conditioning System

WIRING DIAGRAM

FRONT AIR CONDITIONING SYSTEM

REAR AIR CONDITIONING SYSTEM (w/ Rear Air Conditioning System)

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Disconnect the J43 and J48* air conditioning amplifier assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

J43-1 (B) - Body ground

Engine switch off

11 to 14 V

J48-4 (+B2) - Body ground*

Engine switch off

11 to 14 V
  • *: w/ Rear Air Conditioning System
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the J43 and J48* air conditioning amplifier assembly connector.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Active test.

(f) Perform the Active Test according to the display on the Techstream.

Body Electrical > Air Conditioner > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Air Mix Servo Targ Pulse(D)

No. 1 air conditioning radiator damper servo sub-assembly (driver side air mix) pulse

Min.: 128

Max.: 383

Operates between 165 to 257 pulses

Air Mix Servo Targ Pulse(P)

No. 1 air conditioning radiator damper servo sub-assembly (front passenger side air mix) pulse

Min.: 128

Max.: 383

Operates between 255 to 347 pulses

Air Outlet Servo Pulse (D)

No. 3 air conditioning radiator damper servo sub-assembly pulse

Min.: 128

Max.: 383

Operates between 164 to 256 pulses

Air Inlet Damper Targ Pulse

No. 1 blower damper servo sub-assembly pulse

Min.: 128

Max.: 383

Operates between 220 to 256 pulses

Rear Air Mix Servo Targ Pulse

Rear No. 2 cooling unit damper servo sub-assembly pulse*

Min.: 128

Max.: 383

Operates between 254 to 299 pulses

Air Outlet Servo Pulse (P)

No. 1 air conditioning radiator damper servo sub-assembly (front passenger side mode) pulse

Min.: 128

Max.: 383

Operates between 256 to 348 pulses

A/O Servo Pulse(F&R D)

Rear No. 1 cooling unit damper servo sub-assembly pulse*

Min.: 128

Max.: 383

Operates between 200 to 276 pulses

A/O Servo Pulse(Rr D)

No. 2 air conditioning radiator damper servo sub-assembly pulse

Min.: 128

Max.: 383

Operates between 158 to 260 pulses
Body Electrical > Air Conditioner > Active Test

Tester Display

Air Mix Servo Targ Pulse(D)
Body Electrical > Air Conditioner > Active Test

Tester Display

Air Mix Servo Targ Pulse(P)
Body Electrical > Air Conditioner > Active Test

Tester Display

Air Outlet Servo Pulse (D)
Body Electrical > Air Conditioner > Active Test

Tester Display

Air Inlet Damper Targ Pulse
Body Electrical > Air Conditioner > Active Test

Tester Display

Rear Air Mix Servo Targ Pulse
Body Electrical > Air Conditioner > Active Test

Tester Display

Air Outlet Servo Pulse (P)
Body Electrical > Air Conditioner > Active Test

Tester Display

A/O Servo Pulse(F&R D)
Body Electrical > Air Conditioner > Active Test

Tester Display

A/O Servo Pulse(Rr D)
  • *: w/ Rear Air Conditioning System

OK:

Arm of the damper servo motor selected in the Active Test operates smoothly.

(g) According to the test result, proceed to the next step.

Result

Proceed to

All of the damper servo motors are normal

A

One of the damper servo motors is malfunctioning

B

All of the front damper servo motors are malfunctioning

C

All of the rear damper servo motors are malfunctioning

D
A

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

C

GO TO STEP 10

D

GO TO STEP 11

B

3.

SYSTEM CHECK

(a) According to the test result, proceed to the next step.

Result

Proceed to

Only the No. 1 blower damper servo sub-assembly is malfunctioning

A

Only the No. 1 air conditioning radiator damper servo sub-assembly (driver side air mix) is malfunctioning

B

Only the No. 1 air conditioning radiator damper servo sub-assembly (front passenger side air mix) is malfunctioning

Only the No. 1 air conditioning radiator damper servo sub-assembly (front passenger side mode) is malfunctioning

Only the No. 2 air conditioning radiator damper servo sub-assembly is malfunctioning

C

Only the No. 3 air conditioning radiator damper servo sub-assembly is malfunctioning

D

Only the rear No. 1 cooling unit damper servo sub-assembly is malfunctioning

E

Only the rear No. 2 cooling unit damper servo sub-assembly is malfunctioning

F
B

GO TO STEP 5

C

GO TO STEP 6

D

GO TO STEP 7

E

GO TO STEP 8

F

GO TO STEP 9

A

4.

REPLACE NO. 1 BLOWER DAMPER SERVO SUB-ASSEMBLY

(a) Replace the No. 1 blower damper servo sub-assembly.

Click here

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (NO. 1 BLOWER DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)
B

GO TO STEP 5

5.

REPLACE NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY

(a) Replace the No. 1 air conditioning radiator damper servo sub-assembly.

Click here

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)
B

GO TO STEP 10

6.

REPLACE NO. 2 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY

(a) Replace the No. 2 air conditioning radiator damper servo sub-assembly.

Click here

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (NO. 2 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)
B

GO TO STEP 10

7.

REPLACE NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY

(a) Replace the No. 3 air conditioning radiator damper servo sub-assembly.

Click here

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)
B

GO TO STEP 10

8.

REPLACE REAR NO. 1 COOLING UNIT DAMPER SERVO SUB-ASSEMBLY

(a) Replace the rear No. 1 cooling unit damper servo sub-assembly.

Click here

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (REAR NO. 1 COOLING UNIT DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)
B

GO TO STEP 11

9.

REPLACE REAR NO. 2 COOLING UNIT DAMPER SERVO SUB-ASSEMBLY

(a) Replace the rear No. 2 cooling unit damper servo sub-assembly.

Click here

HINT:

Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (REAR NO. 2 COOLING UNIT DAMPER SERVO SUB-ASSEMBLY WAS DEFECTIVE)
B

GO TO STEP 11

10.

REPLACE AIR CONDITIONING HARNESS ASSEMBLY

(a) Replace the air conditioning harness assembly.

Click here

HINT:

Since the air conditioning harness assembly cannot be inspected while it is removed from the vehicle, replace the air conditioning harness assembly with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (AIR CONDITIONING HARNESS ASSEMBLY WAS DEFECTIVE)
B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

11.

REPLACE NO. 2 AIR CONDITIONING HARNESS ASSEMBLY

(a) Replace the No. 2 air conditioning harness assembly.

Click here

HINT:

Since the air conditioning harness assembly cannot be inspected while it is removed from the vehicle, replace the air conditioning harness assembly with a new or known good one and check that the condition returns to normal.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Body Electrical / Air Conditioner / Trouble Codes.

(f) Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTC B1497/97 is not output

A

DTC B1497/97 is output

B
A

END (NO. 2 AIR CONDITIONING HARNESS ASSEMBLY WAS DEFECTIVE)
B

REPLACE NO. 2 AIR CONDITIONING HARNESS ASSEMBLY

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