Test Description

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

2: This step verifies that the condition that set the DTC is present.

DTC B0159

Step	Action	Value(s)	Yes	No
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Install a scan tool. Turn ON the ignition, with the engine OFF. Select the Heating and Air Conditioning display DTC function on the scan tool. Does the scan tool indicate that B0159 is a current DTC?	-	Go to Step 3	Go to Diagnostic Aids
3	Turn OFF the ignition. Disconnect the ambient air temperature sensor. Turn ON the ignition, with the engine OFF. Measure the voltage from the signal circuit of the ambient air temperature sensor to a good ground. Does the voltage measure near the specified value?	5 V	Go to Step 4	Go to Step 5
4	Measure the voltage from the signal circuit to the low reference circuit of the ambient air temperature sensor. Does the voltage measure near the specified value?	5 V	Go to Step 7	Go to Step 6
5	Test the signal circuit of the ambient air temperature sensor for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 8
6	Test the low reference circuit of the ambient air temperature sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 8
7	Inspect for poor connections at the harness connector of the ambient air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 9
8	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 . Did you find and correct the condition?	-	Go to Step 11	Go to Step 10
9	Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement . Did you complete the replacement?	-	Go to Step 11	-
10	Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 11	-
11	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