Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Evaporator Temperature Circuit (B1417/17)

DESCRIPTION

The No. 2 air conditioning harness assembly is installed on the evaporator in the rear air conditioner unit to detect the temperature of the cooled air that has passed through the evaporator, which is used to control the air conditioning system. It sends signals to the air conditioning amplifier assembly. The resistance of the No. 2 air conditioning harness assembly changes in accordance with the temperature of the cooled air that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies voltage (5 V) to the No. 2 air conditioning harness assembly and reads voltage changes as the resistance of the No. 2 air conditioning harness assembly changes. This sensor is used for frost prevention.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B1417/17

Evaporator Temperature Circuit

Open or short in rear evaporator temperature sensor circuit

  • No. 2 air conditioning harness assembly
  • Harness or connector
  • Air conditioning amplifier assembly

Memorized

(4 sec. or more)*

  • *: The air conditioning amplifier assembly stores this DTC if the malfunction has occurred for the period of time indicated in the brackets.

WIRING DIAGRAM

PROCEDURE

1.

READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Data List.

(e) Check the value(s) by referring to the table below.

Body Electrical > Air Conditioner > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Evap Temp Sensor (Rear)

No. 2 air conditioning harness assembly

Min.: -29.70°C (-21.46°F)

Max.: 59.55°C (139.19°F)

Actual rear evaporator temperature displayed

-

Body Electrical > Air Conditioner > Data List

Tester Display

Evap Temp Sensor (Rear)

OK:

The display is as specified in the normal condition column.

Result

Proceed to

OK (When troubleshooting according to Problem Symptoms Table)

A

OK (When troubleshooting according to the DTC)

B

NG

C

A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

C

2.

INSPECT NO. 2 AIR CONDITIONING HARNESS ASSEMBLY

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

Click here

(b) Inspect the No. 2 air conditioning harness assembly.

Click here

NG

REPLACE NO. 2 AIR CONDITIONING HARNESS ASSEMBLY

OK

3.

CHECK HARNESS AND CONNECTOR (NO. 2 AIR CONDITIONING HARNESS ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY)

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R52-8 (+) - J48-8 (TEC)

Always

Below 1 Ω

R52-7 (-) - J48-21 (SG-8)

Always

Below 1 Ω

R52-8 (+) or J48-8 (TEC) - Other terminals and body ground

Always

10 kΩ or higher

R52-7 (-) or J48-21 (SG-8) - Other terminals and body ground

Always

10 kΩ or higher

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

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