HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: DESCRIPTION (2008 Sequoia)

Last Modified: 11-29-2007		1.6 C
Service Category: Vehicle Interior	Section: Heating/Air Conditioning
Model Year: 2008	Model: Sequoia	Doc ID: RM000003F00000X
Title: HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: DESCRIPTION (2008 Sequoia)

DTC

B1417/17

Rear Evaporator Temperature Sensor Circuit

DESCRIPTION

The No. 2 air conditioning harness (rear evaporator temperature sensor) is installed on the evaporator in the rear air conditioning unit to detect the temperature of the cooled air that has passed through the evaporator and to control the rear air conditioner. It sends signals to the air conditioning amplifier. The signals change in accordance with the resistance of the No. 2 air conditioning harness (rear evaporator temperature sensor). As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases. The air conditioning amplifier applies a voltage (5 V) to the No. 2 air conditioning harness (rear evaporator temperature sensor) and reads voltage changes as changes in the resistance of the No. 2 air conditioning harness (rear evaporator temperature sensor). This sensor is used for frost prevention.

DTC Code	DTC Detection Condition	Trouble Area
B1417/17	Open or short in rear evaporator temperature sensor circuit	No. 2 air conditioning harness (rear evaporator temperature sensor) Harness or connector between No. 2 air conditioning harness (rear evaporator temperature sensor) and air conditioning amplifier Air conditioning amplifier

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1.	READ VALUE USING TECHSTREAM (AMBIENT TEMP SENS (REAR))

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

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

(e) According to the display on the Techstream, read the Data List.

Air Conditioner

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Ambient Temp Sens (Rear)

Evaporator fin thermistor /

Min.: -29.7°C (-21.46°F)

Max.: 59.6°C (139.28°F)

Actual rear evaporator temperature is displayed

Open circuit: -29.7°C (-21.46°F)

Short circuit: 59.6°C (139.28°F)

OK:

The display is as specified in the normal condition.

Result

Result	Proceed to
NG	A
OK (When troubleshooting according to Problem Symptoms Table)	B
OK (When troubleshooting according to the DTC output)	C

2.	INSPECT NO. 2 AIR CONDITIONING HARNESS (REAR EVAPORATOR TEMPERATURE SENSOR)

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
7 (-) - 8 (+)	-10°C (14°F)	7.30 to 9.10 kΩ
	-5°C (23°F)	5.65 to 6.95 kΩ
	0°C (32°F)	4.40 to 5.35 kΩ
	5°C (41°F)	3.40 to 4.15 kΩ
	10°C (50°F)	2.70 to 3.25 kΩ
	15°C (59°F)	2.14 to 2.58 kΩ
	20°C (68°F)	1.71 to 2.05 kΩ
	25°C (77°F)	1.38 to 1.64 kΩ
	30°C (86°F)	1.11 to 1.32 kΩ

HINT:

Touching the thermistor even slightly may change the resistance value. Be sure to hold the connector of the thermistor.
When measuring, the thermistor temperature must be the same as the ambient temperature.
As the temperature increases, the resistance decreases (see the graph).

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

(a) Disconnect the P9 No. 2 air conditioning harness connector.

(b) Disconnect the H67 air conditioning amplifier connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
P9-8 (+) - H67-4 (TEC)	Always	Below 1 Ω
P9-7 (-) - H67-19 (SGND)	Always	Below 1 Ω
P9-8 (+) or H67-4 (TEC) - Body ground	Always	10 kΩ or higher
P9-7 (-) or H67-19 (SGND) - Body ground	Always	10 kΩ or higher

(d) Reconnect the air conditioning amplifier connector.

(e) Reconnect the No. 2 air conditioning harness connector.