Hummer H2. Manual - part 212

Conditions for Clearing the DTC 

z

The VCIM detects the microphone connected for 5 consecutive 100 millisecond cycles.  

z

A history DTC clears after 50 malfunction free ignition cycles.  

z

The VCIM receives the clear DTC command from the scan tool.  

Test Description 

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

2: This step checks that the VCIM is sending out the proper supply voltage.  

DTC B2455 

Step

Action

Value

(s)

Yes

No

Schematic Reference:OnStar Schematics 
Connector End View Reference:Cellular Communication Connector End Views

1

Did you perform the Cellular Communications Diagnostic 
System Check?

-

Go to 
Step 
2

Go to Diagnostic 
System Check - 
Cellular 
Communication

2

1. Turn OFF the ignition.  

2. Disconnect the cellular microphone connector.  

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

4. Measure the voltage from the cellular microphone 

signal circuit to a good ground.  

Does the voltage measure greater than the specified 
value?

9 V

Go to 
Step 
3

Go to Step 4

3

Test the drain wire circuit for an open. Refer to Circuit 
Testing and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to 
Step 
10

Go to Step 5

4

Test the cellular microphone signal circuit for an open. 
Refer to Circuit Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

-

Go to 
Step 
10

Go to Step 7

5

Test the cellular microphone signal circuit for a short to 
voltage. Refer to Circuit Testing and Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

-

Go to 
Step 
10

Go to Step 6

6

Inspect for poor connections at the harness connector of 
the cellular microphone. Refer to Testing for 
Intermittent Conditions and Poor Connections and 
Connector Repairs in Wiring Systems. 

-

Go to 
Step 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2

  

DTC B2470 

Circuit Description 

The cellular portion of the cellular and navigation antenna is connected to the vehicle communication interface 
module (VCIM) with a RG-174 coax cable. The VCIM polls the data from the antenna once every second. 

Conditions for Running the DTC 

z

The ignition must be in the RUN or ACC position.  

z

The system voltage is at least 9.5 volts and no more than 15.5 volts.  

z

All the above conditions are present for greater than 1 second.  

Conditions for Setting the DTC 

z

The VCIM does not detect the presence of the cellular antenna  

z

All the above conditions are present for greater than 1 second.  

Action Taken When the DTC Sets 

z

The OnStar(R) status LED turns RED.  

z

The vehicle is unable to connect to the OnStar(R) Call Center. 

Did you find and correct the condition?

10

Go to Step 8

7

Inspect for poor connections at the harness connector of 
the vehicle communication interface module (VCIM). 
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 
10

Go to Step 9

8

Replace the cellular microphone. Refer to OnStar 
Microphone Replacement . 
Did you complete the replacement?

-

Go to 
Step 
10

-

9

Replace the VCIM. Refer to Communication Interface 
Module Replacement .Did you complete the 
replacement?

IMPORTANT:

Perform the OnStar(R) setup procedure.

-

Go to 
Step 
10

-

10

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 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2

  

Conditions for Clearing the DTC 

z

The VCIM detects the presence of the cellular and navigation antenna.  

z

A history DTC clears after 50 malfunction free ignition cycles.  

z

The VCIM receives the clear DTC command from the scan tool.  

Test Description 

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

2: This step checks the condition of the cellular and navigation antenna.  

3: This step tests the condition of the cellular antenna coax and for proper ground of the cellular antenna. 

DTC B2470 

Step

Action

Value Yes

No

Schematic Reference:OnStar Schematics 
Connector End View Reference:Cellular Communication Connector End Views

1

Did you perform the Cellular Communication Diagnostic 
System Check?

-

Go to 

Step 

2

Go to Diagnostic System 

Check - Cellular 

Communication

2

Inspect the cellular and navigation antenna assembly for 
damage. 
Is the antenna assembly damaged?

-

Go to 

Step 

7

Go to Step 3

3

1. Disconnect the cellular antenna coax from the 

vehicle communication interface module (VCIM).  

2. Measure the resistance between the center 

conductor and the outer metal shield.  

Does the meter read out of limits?

-

Go to 

Step 

4

Go to Step 5

4

1. Disconnect the cellular antenna coax from the 

cellular and navigation antenna assembly maroon 
connector.  

2. Measure the resistance of the cellular antenna coax 

center conductor from end to end.  

Does the resistance measure greater than the specified 
value?

1 

ohm

Go to 

Step 

8

Go to Step 6

5

Inspect for poor connections at the harness connector of 
the VCIM. 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 

10

Go to Step 9

Inspect for poor connections at the harness connector of 
the cellular and navigation antenna. Refer to Testing for 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2

  

DTC B2476 

Circuit Description 

The OnStar(R) button assembly consists of three buttons, Call/Answer, OnStar(R) Call Center and OnStar(R) 
Emergency. Ten volts is supplied to the button assembly on the Keypad Supply Voltage circuit. Each of the 
buttons, when pressed, completes the circuit across a resister allowing a specific voltage to be returned to the 
vehicle communication interface module (VCIM) on the Keypad Signal circuit. Depending upon the voltage 
range returned, the VCIM is able to identify which button has been pressed. 

Conditions for Running the DTC 

z

The ignition must be in the RUN or ACC position.  

z

The system voltage is at least 9.5 volts and no more than 15.5 volts.  

z

All the above conditions are present for greater than 300 ms.  

Conditions for Setting the DTC 

z

The VCIM powers the button assembly through the keypad supply voltage circuit for 11.5 ms, turns the 
power off, then waits for 50 ms and sees a voltage value greater than 1.8 volts on this circuit.  

z

The above conditions are present for greater than 300 ms.  

Action Taken When the DTC Sets 

z

The VCIM will ignore all inputs from the OnStar(R) button assembly.  

z

No calls can be placed.  

6

Intermittent Conditions and Poor Connections and 
Connector Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to 

Step 

10

Go to Step 7

7

Replace the cellular and navigation antenna. Refer to 
Antenna Assembly Replacement - Cellular and 
Navigation . 
Did you complete the replacement?

-

Go to 

Step 

10

-

8

Replace the cellular antenna coax. 
Did you complete the replacement?

-

Go to 

Step 

10

-

9

Replace the VCIM. Refer to Communication Interface 
Module Replacement . 
Did you complete the replacement?

-

Go to 

Step 

10

-

10

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 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2