The radio supplies voltage to the audio steering wheel control 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 radio then identifies the selection to activate the feature, otherwise sends a serial data message that is received by the controlled component activating the feature.

Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

Connector End View Reference

Electrical Information Reference

Caution: Refer to SIR Caution in the Preface section.

Important: It is recommended that Component Testing is performed before Circuit Testing when diagnosing steering wheel controls.

1. Ignition OFF, disconnect the harness connector at the left and right steering wheel control switches.
2. Ignition ON, radio ON, test for 8.5-10.5 volts between the supply voltage circuit and ground at the right switch harness connector.

⇒	If less than 8.5 volts test the voltage supply circuit for a short to ground or an open/ high resistance. If circuit test normal, replace the radio.

⇒	If greater than 10.5 volts, test the voltage supply circuit for short to voltage. If circuit test normal, replace the radio.

3. Test for 8.5-10.5 volts from the supply voltage circuit and toggle to the signal circuits at the left and right switch harness connectors.

⇒	If less than 8.5 volts, test the signal circuit for an open/ high resistance. If the circuit test normal, replace the radio.

⇒	If greater than 10.5 volts, test the signal circuit for short to voltage. If the circuit test normal, replace the radio.

4. Ignition OFF, reconnect the right switch.
5. Ignition ON, radio ON, test for 8.5-10.5 volts between the supply voltage circuit and signal circuit at the left switch harness connector.

⇒	If less than 8.5 volts test the voltage supply circuit to the left switch for a short to ground or an open/ high resistance. If circuit test normal, test or replace the right switch.

⇒	If greater than 10.5 volts, repair the voltage supply circuit for a short to B+.

6. Test for 1-3 volts between the signal circuit and ground at the left switch harness connector when pressing the mute button.

⇒	If less than 1-volt, test the signal circuit for a short to ground. If the circuit test is normal, test or replace the right switch.

7. If circuit test normal, test or replace switch.

Caution: Refer to SIR Caution in the Preface section.

1. Ignition OFF, disconnect the harness connector at the suspect switch.
2. Test the right switch for 2360-2400 ohms of resistance between both remote radio control supply voltage terminals with the switch in the open position.

⇒	If the resistance is not between 2360-2400 ohms of resistance, replace the faulty switch.

3. Test for infinite resistance between the supply voltage terminal and the signal terminal with the switch in the open position.

⇒	If less than infinite resistance, replace the switch.

4. Test resistance values between the supply voltage terminal and the signal terminal with the switch closed in each position and verify readings are approximate to what the schematic reads.

⇒	If values do not, replace the switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.