For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Left Steering Wheel Control Switch Signal | 1 | B3647 08, B3648 08, B3649 04, B3649 08 | 1 | B3647 5A, B3648 5A, B3649 5A
Right Steering Wheel Control Switch Signal | 1 | B3644 08, B3645 08, B3646 04, B3646 08 | 1 | B3644 5A, B3645 5A, B3646 5A
Low Reference | -- | 1 | 1 | --
1. Steering Wheel Controls Inoperative

### Circuit/System Description

The steering column control module (SCCM) supplies voltage to the audio steering wheel control multiple momentary contact switches and monitors the return signal. Each switch is associated to a set resistance value, when pressed a specific voltage drop occurs through a series of resistors unique to that switch. The SCCM identifies the selection, then sends a serial data message that is received by the component controlled, activating the feature.

### Reference Information

#### Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Steering Wheel Controls Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the appropriate scan tool parameters for the left and right steering wheel control switches while pressing and releasing the individual switches. The scan tool parameter should change state when the switch is pressed and released.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the steering wheel control switch.
2. Ignition OFF, test for less than 2.0 ohms between the appropriate low reference circuit terminal listed below and ground.

• | right steering wheel control switch terminal 3

• | left steering wheel control switch terminal 2

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the SCCM.

3. Ignition ON, test for 4.8-5.2 volts between the appropriate signal circuit terminal listed below and ground.

• | right steering wheel control switch terminal 6

• | left steering wheel control switch terminal 1

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the SCCM.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SCCM.

4. If all circuits test normal, test or replace the steering wheel control switch.

### Component Testing

1. Disconnect the harness connector at the appropriate steering wheel control switch.
2. Connect a DMM between the appropriate terminals listed below of the appropriate steering wheel control switch:

• | right steering wheel control switch terminal 6 and terminal 3

• | left steering wheel control switch terminal 1 and terminal 2

⇒ | If any of the resistance measurements for the individual switches are not within the specified resistance values, replace the steering wheel control switch.

#### Left Steering Wheel Switch Resistance

Function Switch | Minimum Resistance Value | Maximum Resistance Value
--- | --- | ---
Scroll Wheel Up | 49.7 Ohms | 53.7 Ohms
Scroll Wheel Down | 117.5 Ohms | 121.5 Ohms
Scroll Wheel Press | 217.5 Ohms | 221.5 Ohms
Voice/Station Presets | 397 Ohms | 401 Ohms
Phone/CD Changer | 756 Ohms | 760 Ohms
No Switch Pressed | 1855 Ohms | 1859 Ohms

#### Right Steering Wheel Switch Resistance

Function Switch | Minimum Resistance Value | Maximum Resistance Value
--- | --- | ---
Scroll Wheel Up | 60.8 Ohms | 64.8 Ohms
Scroll Wheel Down | 160.5 Ohms | 164.5 Ohms
Up Key/Station Seek | 359.7 Ohms | 363.7 Ohms
Down Key/Station Seek | 919 Ohms | 923 Ohms
No Switch Pressed | O.L. | O.L.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Steering Wheel Control Switch Assembly Replacement

• | Control Module References for SCCM replacement, setup, and programming