Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM0000018MX004X
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: AIR CONDITIONING: AIR CONDITIONING SYSTEM: 12; Ambient Temperature Sensor Circuit; 2007 MY LX470 [08/2006 -        ]

DTC

12

Ambient Temperature Sensor Circuit

DESCRIPTION

This sensor detects the ambient temperature and sends the appropriate signals to the A/C amplifier.

DTC No.

Detection Item

Trouble Area

12

Open or short in ambient temperature sensor circuit
  • Ambient temperature sensor
  • Harness or connector between ambient temperature sensor and A/C amplifier
  • A/C amplifier

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK AIR CONDITIONING AMPLIFIER

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

(b) Turn the ignition switch ON.

(c) Measure the voltage between terminals TAM (A48-7) and FRSG (A48-18) of the A/C amplifier connector at each temperature.

Standard voltage:

1.35 to 1.75 V at 25 °C (77°F)

0.85 to 1.25 V at 40 °C (104°F)

HINT:

  • As the temperature increases, the voltage decreases.
  • However, if DTC 12 is displayed, check and replace the A/C amplifier.
OK

REPLACE AIR CONDITIONING AMPLIFIER

NG

2.

INSPECT AMBIENT TEMPERATURE SENSOR

(a) Disconnect the A1 ambient temperature sensor connector.

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

Standard resistance:

1.6 to 1.8 kΩ at 25 °C (77°F)

0.5 to 0.7 kΩ at 40 °C (104°F)

HINT:

As the temperature increases, the resistance decreases.

NOTICE:

When installing the ambient temperature sensor, be sure to connect the sensor connector before connecting the battery.
NG

REPLACE AMBIENT TEMPERATURE SENSOR

OK

3.

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

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

REPLACE AIR CONDITIONING AMPLIFIER