GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The steering wheel controls are simple momentary contact switches that connect a series of resistors so that each switch selection corresponds to a fixed resistance value. The dash integration module (DIM) determines which switch has been pressed by the voltage drop across the corresponding resistance value.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2805 Steering Wheel Controls HVAC Switch Circuit Malfunction

Conditions for Running the DTC

The DIM must be powered.

Conditions for Setting the DTC

One of the HVAC switches must be active (stuck) for at least 30 seconds.

Action Taken When the DTC Sets

The DIM will disable all of the steering wheel control switches while the fault is present.

Conditions for Clearing the DTC

    • The DTC will become history if the DIM no longer detects a failure.
    • The history DTC will clear after 50 fault-free ignition cycles.
    • The DTC can be cleared with a scan tool.

Diagnostic Aids

Switch Position

Counts

No Input

0

TEMP DOWN

136

TEMP UP

162

FAN DOWN

81

FAN UP

108

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step verifies that one of the HVAC switches of the steering wheel controls is active. The value given is the normal condition that exists when no switch is activated.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC 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 Steering Wheel Controls parameter in the Dash Integration Module data list.

Does the scan tool indicate that the counts are within the specified range?

0-7 Counts

Go to Diagnostic Aids

Go to Step 3

3

Replace the steering wheel controls. Refer to Steering Wheel HVAC Control Assembly Replacement .

Did you complete the replacement?

--

Go to Step 4

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4

  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