Hummer H3. Manual — part 1189

4

1. Disconnect the cellular antenna

coax from the VCIM.

2. Measure the resistance of the

cellular antenna coax connector
from end to end.

Does the resistance measure greater
than the specified value?

1 ohms

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 .
Did you find and correct the
condition?

-

Go to Step

10

Go to Step 9

6

Inspect for poor connections at the
harness connector of the cellular
antenna. Refer to Testing for
Intermittent Conditions and Poor
Connections and Connector
Repairs .
Did you find and correct the
condition?

-

Go to Step

10

Go to Step 7

7

Replace the cellular antenna. Refer to
Cellular Communications/Digital
Radio Antenna Replacement.
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 Control
Module References for replacement,
setup and programming.
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

-

2007 Hummer H3

2007 ACCESSORIES AND EQUIPMENT Cellular, Entertainment and Navigation - H3

DTC B2476

Circuit Description

The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center and
OnStar® Emergency. Ten volts are 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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2476 Cellular Phone Select Service Switch Malfunction (3 button assembly)

Conditions for Running the DTC

The ignition must be in the RUN or ACC position.

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

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

Conditions for Setting the DTC

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

The above conditions are present for greater than 300 milliseconds.

Action Taken When the DTC Sets

The VCIM will ignore all inputs from the OnStar® button assembly.

No calls can be placed.

The OnStar® status LED turns RED.

Conditions for Clearing the DTC

text.

Does the DTC reset?

Go to Step 2 System OK

2007 Hummer H3

2007 ACCESSORIES AND EQUIPMENT Cellular, Entertainment and Navigation - H3

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

A history DTC clears after 50 malfunction-free ignition cycles.

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 B2476

Step

Action

Values

Yes

No

Schematic Reference: OnStar Schematics
Connector End View Reference: Entertainment/Communication Connector End
Views

1

Did you perform the Diagnostic
System Check - Vehicle?

-

Go to Step 2

Go to
Diagnostic
System
Check -
Vehicle

2

1. Turn OFF the ignition.

2. Disconnect the OnStar® button

assembly connector.

3. Turn ON the ignition, with the

engine OFF.

4. Measure the voltage from the

keypad supply voltage circuit to
a good ground.

Does the voltage measure greater than
the specified value?

9 V

Go to Step 4 Go to Step 3

3

Test the keypad supply voltage circuit
for an open or short to ground. Refer
to Circuit Testing and Wiring
Repairs .
Did you find and correct the

-

Go to Step

2007 Hummer H3

2007 ACCESSORIES AND EQUIPMENT Cellular, Entertainment and Navigation - H3

condition?

11

Go to Step 8

4

Test the keypad supply voltage circuit
for a short to voltage. Refer to
Circuit Testing and Wiring
Repairs .
Did you find and correct the
condition?

-

Go to Step

11

Go to Step 5

5

Test the keypad ground circuit for an
open. Refer to Circuit Testing and
Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step

11

Go to Step 6

6

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

-

Go to Step

11

Go to Step 7

7

Inspect for poor connections at the
harness connector of the OnStar®
button assembly. 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 vehicle
communication interface module
(VCIM). 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 OnStar® button
assembly. Refer to OnStar Button
Assembly Replacement.
Did you complete the replacement?

-

Go to Step

11

-

2007 Hummer H3

2007 ACCESSORIES AND EQUIPMENT Cellular, Entertainment and Navigation - H3