Hummer H2. Manual - part 1938

2: 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 HVAC Diagnostic System Check?

-

Go to 

Step 2

Go to Diagnostic 

System Check - 

HVAC Systems - 

Automatic

2

1. Install a scan tool.  

2. Turn ON the ignition, with the engine OFF.  

3. 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

1. Turn OFF the ignition.  

2. Disconnect the ambient air temperature sensor.  

3. Turn ON the ignition, with the engine OFF.  

4. 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 in 
Wiring Systems. 
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 in Wiring Systems. 
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 in Wiring Systems. 
Did you find and correct the condition?

-

Go to 

Step 

11

Go to Step 9

Inspect for poor connections at the harness connector of the 
HVAC control module. Refer to Testing for Intermittent 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

DTC B0164 

Circuit Description 

The inside air temperature sensor assembly allows the HVAC control module to monitor the temperature of the 
air inside the passenger compartment. The module applies 5 volts to internal input resistors that are connected to
the signal circuit of the inside air temperature sensor assembly. The module provides ground to the inside air 
temperature sensor assembly through the low reference circuit. The HVAC control module monitors the voltage 
drop across the inside air temperature sensor assembly and uses the input for automatic control calculations. 
When the air temperature is cold, the resistance of the sensor is high and the voltage signal is high. When the air 
temperature is hot, the resistance of the sensor is low and the voltage signal is low. 

Conditions for Running the DTC 

z

Battery voltage to the HVAC control module is greater than 8.7 V and less than 16.5 V.  

z

The ignition is turned ON.  

Conditions for Setting the DTC 

The HVAC control module determines that the voltage applied to the input for the inside air temperature sensor 
assembly is less than 0.09 V or greater than 4.9 V. 

Action Taken When the DTC Sets 

The HVAC control module uses a default value of 55° C (131° F) for the Inside Air Temp. parameter. This 
value will be displayed on the scan tool. 

Conditions for Clearing the DTC 

z

The DTC will become history if the HVAC control module no longer detects the condition that set the 
DTC.  

8

Conditions and Poor Connections and Connector 
Repairs in Wiring Systems. 
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 HVAC 
Control Module Replacement . 
Did you complete the replacement?

-

Go to 

Step 

11

-

11

1. Use the scan tool in order to clear the DTCs.  

2. 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

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

z

The history DTC will clear after 100 fault free ignition cycles.  

z

The DTC can be cleared with a scan tool.  

Diagnostic Aids 

If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring 
Systems. 

Test Description 

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

2: Verifies that the condition that set the DTC is present.  

DTC B0164 

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

1. Install a scan tool.  

2. Turn ON the ignition, with the engine OFF.  

3. Select the Heating and Air Conditioning display DTC 

function on the scan tool.  

Does the scan tool indicate that B0164 is a current DTC?

-

Go to 

Step 3 Go to Diagnostic Aids

3

1. Turn OFF the ignition.  

2. Disconnect the inside air temperature sensor assembly. 

3. Turn ON the ignition, with the engine OFF.  

4. Measure the voltage from the signal circuit of the 

inside air temperature sensor assembly 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 inside air temperature sensor 
assembly. 
Does the voltage measure near the specified value?

5 V

Go to 

Step 7

Go to Step 6

Test the signal circuit of the inside air temperature sensor 
assembly for an open, high resistance, short to ground, or 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

DTC B0174, B0179, B0510, OR B0515 

Circuit Description 

The following DTC's are for the air temperature sensors located in the discharge air ducts: 

z

B0174 is for the upper left air temperature sensor.  

z

B0179 is for the lower left air temperature sensor.  

z

B0510 is for the upper right air temperature sensor.  

z

B0515 is for the lower right air temperature sensor.  

Air temperature sensors allow the HVAC control module to monitor the temperature of the discharge air in the 
HVAC ducts. The module applies 5 volts to internal input resistors that are connected to the signal circuits of 
the air temperature sensors. The module provides ground to the air temperature sensors through the low 
reference circuit. The HVAC control module monitors the voltage drop across the air temperature sensors and 
uses the inputs for automatic control calculations. When the duct air temperatures are cold, the resistances of the 

5

short to voltage. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to 

Step 

11

Go to Step 8

6

Test the low reference circuit of the inside air temperature 
sensor assembly 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 

11

Go to Step 8

7

Inspect for poor connections at the harness connector of the 
inside air temperature sensor assembly. 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 

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
in Wiring Systems. 
Did you find and correct the condition?

-

Go to 

Step 

11

Go to Step 10

9

Replace the inside air temperature sensor assembly. Refer to 
Inside Air Temperature Sensor Assembly Replacement .
Did you complete the replacement?

-

Go to 

Step 

11

-

10

Replace the HVAC control module. Refer to HVAC 
Control Module Replacement . 
Did you complete the replacement?

-

Go to 

Step 

11

-

11

1. Use the scan tool in order to clear the DTCs.  

2. 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

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2