031
B1251
IN-CAR TEMPERATURE SENSOR OPEN
GO to Pinpoint Test B
PINPOINT TEST B: IN-CAR TEMPERATURE SENSOR INOPERATIVE
B1 CHECK SENSOR RESISTANCE
NOTE: An open sensor will cause warm air discharge at 18°F (65° C) setting. A shorted sensor will cause cool discharge air at 29°F (85°C) setting.
- Disconnect the A/C ambient air temperature sensor.
- Using an ohmmeter, measure the resistance across the sensor terminals and compare the readings with the following sensor resistance table:
Approximate Temperature
Sensor Resistance Acceptance Range
10-20°C (50-68°F)
37K-58K ohms
20-30°C (68-86°F)
24K- 37K ohms
30-40°C (86-104°F)
16K-24K ohms
Are resistance values within the specified limits?
Yes
No
GO to
B2 .
REPLACE A/C ambient air temperature sensor and bracket. RESTORE vehicle. RETEST system.
B2 CHECK ASPIRATOR INSTALLATION
- Gain access to automatic temperature control sensor.
- Check for proper installation of automatic temperature control sensor hose and elbow.
Is aspirator installed properly and hose connected?
Yes
No
GO to
B3 .
SERVICE automatic temperature control sensor hose and elbow as necessary. RESTORE vehicle. RETEST system.
B3 CHECK CIRCUIT 470 (PK/BK) AT AUTOMATIC TEMPERATURE CONTROL SENSOR
- Turn ignition switch to the RUN position.
- Turn EATC module to NORM A/C position.
- Disconnect automatic temperature control sensor.
- Using a voltmeter, check Circuit 470 (PK/BK) for voltage at sensor connector.
Is voltage 5 volts?
Yes
No
GO to
B5 .
GO to
B4 .
B4 CHECK CIRCUIT 470 (PK/BK) FOR OPEN
- Disconnect connector C227 at EATC module.
- Using an ohmmeter, check Circuit 470 (PK/BK) between EATC module and automatic temperature control sensor for open.
Is there 5 ohms or less?
Yes
No
SERVICE Circuit 470 (PK/BK) for open. RETEST system.
GO to
B5 .
B5 TEST CIRCUIT 470 (PK/BK) FOR SHORT
- Using an ohmmeter connected to a good ground, connect other lead to EATC module connector Pin C227 , Circuit 470 (PK/BK).
Is resistance less than 10,000 ohms?
Yes
No
SERVICE Circuit 470 (PK/BK) for short. RESTORE vehicle. RETEST system.
GO to
B6 .
B6 TEST CIRCUIT 790 (W/O) FOR OPEN
- Using an ohmmeter, connect one lead to EATC module connector Pin C227 , Circuit 790 (W/O) and other lead to automatic temperature control sensor Circuit 790 (W/O).
Is resistance 5 ohms or less?
Yes
No
GO to
B7 .
SERVICE Circuit 790 (W/O).
B7 TEST CIRCUIT 790 (W/O) FOR SHORT
- Using an ohmmeter connected to a good ground, connect other lead to EATC module connector Pin C227 , Circuit 790 (W/O).
Is resistance less than 10,000 ohms?
Yes
No
SERVICE Circuit 790 (W/O) for short. RESTORE vehicle. RETEST system.
REPLACE EATC module. RESTORE vehicle. RETEST system.
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