Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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 Schematics

Connector End View Reference

Electrical Information Reference

Note: It is Recommend that Component Testing be performed before Circuit Testing when diagnosing steering wheel controls.

Caution: Refer to SIR Caution in the Preface section.

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 10-volt reference circuit and ground at the right switch harness connector.

⇒	If less than 8.5 volts, test 10-volt reference circuit for short to ground or open/ high resistance. If circuit test normal, replace radio.

⇒	If greater than 10.5 volts, test the 10-volt reference circuit for short to voltage. If circuit test normal, replace radio.

3. Test for 8.5-10.5 volts from the 10-volt reference 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 to the left switch and ground at the left switch harness connector.

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

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

6. Test for 1-2 volts when pressing the mute button between the signal circuit and ground at the left switch harness connector.

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

7. If all circuits test normal, refer to component testing.

Caution: Refer to SIR Caution in the Preface section.

1. Ignition OFF, disconnect the harness connector at the suspect audio steering wheel control switch.
2. Test the right switch for 2360-2400 ohms of resistance between the 10-volt reference terminal and the remote radio control signal

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

3. Test for infinite resistance between the 10-volt reference 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 10-volt reference 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.

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.