GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The steering wheel controls are momentary contact switches that connect a series of resistors so that each switch selection corresponds to a fixed resistance value. The body control module (BCM) determines which switch has been pressed by the voltage drop across the corresponding resistance value. The BCM supplies voltage to the steering wheel controls through the rear wiper/washer switch supply voltage circuit. The BCM monitors the switch voltage on the remote radio control signal circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2815 Steering Wheel Controls Illegal Resistance Value

Conditions for Running the DTC

This test is run every 125 milliseconds.

Conditions for Setting the DTC

The BCM detects a switch voltage that is higher than normal.

Action Taken When the DTC Sets

The BCM will ignore the switch command.

Conditions for Clearing the MIL/DTC

    • The DTC will become history if the BCM no longer detects a circuit malfunction.
    • The history DTC will clear after 100 fault-free ignition cycles.
    • The DTC can be cleared with a scan tool.

Test Description

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

  1. Tests for the proper operation of the circuit in the low voltage range.

Step

Action

Values

Yes

No

Schematic Reference: Radio/Audio System Schematics

Connector End View Reference: Entertainment Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the SWC Switch Voltage parameter in the Body Control Module data list .

Does the scan tool indicate that the SWC Switch Voltage parameter is near the specified value?

0 V

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

    Caution: Refer to SIR Caution in the Preface section.

  1. Disable the SIR system. Refer to SIR Disabling and Enabling and SIR Disabling and Enabling in SIR.
  2. Turn OFF the ignition.
  3. Disconnect the left steering wheel controls.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the SWC Switch Voltage parameter.

Does the scan tool indicate that the SWC Switch Voltage parameter is near the specified value?

0 V

Go to Step 6

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the right steering wheel controls.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the SWC Switch Voltage parameter.

Does the scan tool indicate that the SWC Switch Voltage parameter is near the specified value?

0 V

Go to Step 7

Go to Step 5

5

Test the remote radio control 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 12

Go to Step 8

6

Inspect for poor connections at the harness connector of the left steering wheel control switch. 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 12

Go to Step 9

7

Inspect for poor connections at the harness connector of the right steering wheel control switch. 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 12

Go to Step 10

8

Inspect for poor connections at the harness connector of the body control module (BCM). 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 12

Go to Step 11

9

Replace the left steering wheel control switch. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column.

Did you complete the replacement?

--

Go to Step 12

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10

Replace the right steering wheel control switch. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column.

Did you complete the replacement?

--

Go to Step 12

--

11

Replace BCM. Refer to Control Module References in Computer/Integrating Systems.

Did you complete the replacement?

--

Go to Step 12

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12

  1. Enable the SIR system. Refer to SIR Disabling and Enabling and SIR Disabling and Enabling in SIR.
  2. Use the scan tool in order to clear the DTCs.
  3. 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