Test Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

2: Verifies that the value displayed is not within the calibrated range.
3: Tests for the proper operation of the circuit in the high voltage range.
4: Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

DTC B0174, B0179, B0510, or B0515

Step	Action	Value(s)	Yes	No
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views
1	Did you perform the HVAC Diagnostic System Check?	-	Go to Step 2	Go to Diagnostic System Check - HVAC Systems - Automatic
2	Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the appropriate Duct Actual parameter in the Heating and Air Conditioning data list. Does the scan tool indicate that the Duct Actual parameter is within the specified range?	5-250 Counts	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Turn OFF the ignition. Disconnect the air temperature sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the appropriate Duct Actual data parameter. Does the scan tool indicate that the Duct Actual data parameter is greater than the specified value?	250 Counts	Go to Step 4	Go to Step 5
4	Turn OFF the ignition. Connect a 3 amp fused jumper wire between the signal circuit of the air temperature sensor and the low reference circuit of the air temperature sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the appropriate Duct Actual data parameter. Does the scan tool indicate that the Duct Actual data parameter is less than the specified value?	5 Counts	Go to Step 8	Go to Step 6
5	Test the appropriate signal circuit of the air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 9
6	Test the appropriate signal circuit of the air temperature sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 7
7	Test the appropriate low reference circuit of the air temperature sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 9
8	Inspect for poor connections at the harness connector of the appropriate air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 10
9	Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 11
10	Replace the air temperature sensor. Refer to the appropriate replacement procedure: Air Temperature Sensor Replacement - Upper Right Air Temperature Sensor Replacement - Upper Left Air Temperature Sensor Replacement - Lower Left Air Temperature Sensor Replacement - Lower Right Did you complete the replacement?	-	Go to Step 12	-
11	Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement?	-	Go to Step 12	-
12	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	-	Go to Step 2	System OK