GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Yukon XL - 2WD 🢒 DTC 🢒 DTC B2476 Cellular Phone Select Service Switch Malfunction

Circuit Description

If the voltage received from the three button assembly to the vehicle interface unit (VIU) is not between a predescribed high and low limit then the VIU will set the DTC.

Conditions for Running the DTC

The ignition must be in the RUN or ACC position and the VIU power must be on. The VIU will run this test every 300 ms during VIU power on.

Conditions for Setting the DTC

If the voltage received from the three button assembly to the VIU is not between a predescribed high and low limit then the VIU will set the DTC.

Action Taken When the DTC Sets

When the code is current the VIU will use the ROM default block for making the Checksum calculations.

Conditions for Clearing the MIL/DTC

The code can be cleared when the VIU does not detect a failure during the last diagnostic cycle.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step inspects the circuits of the three button assembly for shorts, opens and continuity.

    2.

  2. This step verifies the operation of the three button assembly through the Tech 2.

    3.

  3. Using the Tech 2, verify the repair was complete.

Step

Action

Value(s)

Yes

No

1

Did you perform the OnStar® Diagnostic System Check?

--

Go to Step 2

Go to OnStar System Check

2

Test the five keypad circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 3

3

Inspect for poor connections at the harness connector of the three button 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 7

Go to Step 4

4

  1. Activate the cellular phone select service switch.
  2. With a scan tool, observe the Cellular Phone Select Service Switch parameter.
  3. Activate all three OnStar® buttons.

Does the Cellular Phone Select Service Switch parameter change state?

 

Go to Step 6

Go to Step 5

5

Replace the three button assembly. Refer to OnStar Button Assembly Replacement .

Did you complete the replacement?

--

Go to Step 7

--

6

Replace the VIU. Refer to OnStar Vehicle Interface Unit Replacement .

Did you complete the replacement?

--

Go to Step 7

--

7

  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