Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM0000018N3004X
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: AIR CONDITIONING: AIR CONDITIONING SYSTEM: 19; Rear Room Temperature Sensor Circuit; 2007 MY LX470 [08/2006 -        ]

DTC

19

Rear Room Temperature Sensor Circuit

DESCRIPTION

This sensor detects the temperature inside the cabin (rear side) and sends the appropriate signals to the rear A/C amplifier.

DTC No.

Detection Item

Trouble Area

19

Open or short in rear room temperature sensor circuit
  • Rear room temperature sensor
  • Harness or connector between rear room temperature sensor and rear A/C amplifier
  • Rear A/C amplifier

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK AIR CONDITIONING AMPLIFIER

(a) Remove the rear A/C amplifier with the connectors still connected.

(b) Turn the ignition switch ON.

(c) Measure the voltage between terminals TR (A35-7) and SGND (A35-12) of the rear A/C amplifier connector at each temperature.

Standard voltage:

1.8 to 2.2 V at 25°C (77°F)

1.2 to 1.6 V at 40°C (104°F)

HINT:

  • As the temperature increases, the voltage decreases.
  • However, if DTC 19 is displayed, check and replace the A/C amplifier.
OK

REPLACE REAR AIR CONDITIONING AMPLIFIER

NG

2.

INSPECT REAR ROOM TEMPERATURE SENSOR

(a) Disconnect the R33 rear room temperature sensor connector.

(b) Measure the resistance between terminals 1 and 2 of the room temperature sensor connector at each temperature.

Standard resistance:

1.65 to 1.75 kΩ at 25°C (77°F)

0.55 to 0.65 kΩ at 50°C (122°F)

HINT:

  • As the temperature increases, the voltage decreases.
  • However, if DTC 19 is displayed, check and replace the A/C amplifier.
NG

REPLACE REAR ROOM TEMPERATURE SENSOR

OK

3.

CHECK WIRE HARNESS (REAR AIR CONDITIONING AMPLIFIER - REAR ROOM TEMPERATURE SENSOR)
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

REPLACE REAR AIR CONDITIONING AMPLIFIER