GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1998 🢒 Grand Prix 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC 04 Outside Air Temp Sensor Circuit Open

Step

Action

Value(s)

Yes

No

1
  1. Disconnect the ambient outside temperature sensor harness connector.
  2. Place the ignition switch to the RUN position.
  3. Place the heater-A/C control in the AUTO position.
  4. Use a digital multimeter (DMM) in order to measure the voltage between the ambient outside air temperature sensor harness connector terminal A (circuit 735) and ground.

Is the measured voltage within the specified range?

4-6 V

Go to Step 2

Go to Step 3

2

Use a DMM in order to measure the voltage between the ambient outside air temperature sensor harness connector terminal A (circuit 735) and terminal B (circuit 61).

Is the measured voltage within the specified range?

4-6 V

Go to Step 8

Go to Step 9

3
  1. Place the ignition switch in the OFF position.
  2. Disconnect connector C120.
  3. Place the ignition switch in the RUN position.
  4. Use a DMM in order to measure the voltage between the connector C120 (female side) terminal B and ground.

Is the measured voltage within the specified range?

4-6 V

Go to Step 5

Go to Step 4

4
  1. Place the ignition switch in the OFF position.
  2. Disconnect the heater-A/C control harness connector.
  3. Use a DMM in order to measure the resistance between the heater-A/C control harness connector terminal D3 and connector C120 (female side) terminal B (circuit 735).

Is the resistance less than the specified value?

0.5 ohms

Go to Step 7

Got to Step 6

5

Locate and repair a poor connection or an open in circuit 735 (LT GRN/BLK) between connector C120 and the ambient outside air sensor harness connector terminal A.

Is the repair complete?

--

System OK

--

6

Locate and repair a poor connection or an open in circuit 735 (LT GRN/BLK) between the heater-A/C control harness connector and connector C120.

Is the repair complete?

--

System OK

--

7

Replace the heater-A/C control. Refer to Control Assembly Replacement .

Is the repair complete?

--

System OK

--

8

Replace the ambient outside temperature sensor. Refer to Ambient Temperature Sensor Replacement .

Is the repair complete?

--

System OK

--

9

Locate and repair a poor connection or an open in circuit 61 (YEL) between the ambient outside temperature sensor harness connector terminal B and S258.

Is the repair complete?

--

System OK

--