C: A/C AMBIENT AIR TEMPERATURE SENSOR INOPERATIVE

PINPOINT TEST C: A/C AMBIENT AIR TEMPERATURE SENSOR INOPERATIVE

C1 PERFORM EATC ON-BOARD DIAGNOSTICS

- Turn the ignition switch to RUN.
- Press OFF and FLOOR buttons simultaneously and then press AUTOMATIC button within two seconds.
- On-Board Diagnostics may run as long as 30 seconds.
- After self test, record all DTCs and any temperature display readings.
- Press the blue (cooler) button to exit On-Board Diagnosis.

- Are DTCs 040, 041, 042 or 043 displayed and is temperature display reading -40°C (-40°F) or 53°C(128°F)?

- Yes
Go to C2.

- No
Go to C3.

C2 CHECK SENSOR RESISTANCE






NOTE: An open sensor will cause the outside temperature display to read -40°C or -40°F. A shorted sensor will cause the outside temperature display to read 53°C (128°F).

- Disconnect the battery ground cable from battery (this will reset the outside temperature display memory).
- Disconnect the A/C ambient air temperature sensor and bracket.
- Using a ohmmeter, measure the resistance across the two sensor terminals and compare the reading with the sensor resistance table.

- Are resistance values within the specified limits?

- Yes
Go to C3.

- No
Replace A/C ambient air temperature sensor and bracket. Restore vehicle. Retest system.

C3 CHECK CIRCUIT 767 (LB/O) AT A/C AMBIENT AIR TEMPERATURE SENSOR

- Turn ignition switch to the RUN position.
- Turn EATC module to NORM A/C position.
- Disconnect A/C ambient air temperature sensor and bracket.
- Using voltmeter, check Circuit 767 (LB/O) for voltage at sensor connector.

- Is voltage 5 volts?

- Yes
Go to C6.

- No
Go to C4.

C4 CHECK CIRCUIT 767 (LB/O) AT EATC MODULE

- Using voltmeter, check Circuit 767 (LB/O) at EATC module Pin 1 for voltage.

- Is voltage 5 volts?

- Yes
Go to C5.

- No
Replace EATC module. Restore vehicle. Retest system.

C5 CHECK CIRCUIT 767 (LB/O) FOR OPEN

- Turn ignition switch to the OFF position.
- Using a jumper connected to a known good ground, connect other end to Circuit 767 (LB/O) at sensor connector.
- Using an ohmmeter connected to a known good ground, connect second lead to EATC module connector Pin 1, Circuit 767 (LB/O).
- Measure resistance.

- Is resistance 5 ohms or less?

- Yes
Go to C6.

- No
Service circuit 767 (LB/O) for open. Restore vehicle. Retest system.

C6 CHECK CIRCUIT 470 (PK/BK)

- Connect jumper to Circuit 470 (PK/BK) at sensor connector.
- Using an ohmmeter connected to a known good ground, connect second lead to module connector Pin 2, Circuit 470 (PK/BK).
- Measure resistance.

- Is resistance 5 ohms or less?
- Yes
Replace A/C ambient air temperature sensor and bracket. Restore vehicle. Retest system.

- No
Service circuit 470 (PK/BK) for open. Restore vehicle. Retest system.