Steering Wheel Controls Inoperative Audio/Temp
Diagnostic Fault Information
Important: Always perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit/System Description
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. The temperature up/down switch is part of this circuit, if equipped.
Diagnostic Aids
• | This diagnostic is for the audio steering wheel controls. |
• | Before diagnosis of the steering wheel controls, ensure the primary controls of the associated component are functioning properly. |
• | Review with the schematic when testing switch resistance values. |
• | If a single switch function is inoperative, test the suspect switch. Refer to component testing. |
• | A poor connection at the right switch could cause both banks of switches to be inoperative or malfunction. |
Reference Information
Schematic Reference
Steering Wheel Schematics
Connector End View Reference
Entertainment Connector End Views
Electrical Information Reference
Circuit/System Testing
Note: It is Recommend that Component Testing is performed before Circuit Testing when diagnosing steering wheel controls.
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the left and right steering wheel control switches.
- 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 supply voltage 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 supply
voltage circuit for short to voltage. If circuit test normal, replace the radio. |
- Test for 8.5-10.5 volts between the supply voltage circuit and toggle to the signal circuit at the left and right switch harness connectors.
⇒ | If less than 8.5 volts test the signal circuit for an open/ high resistance. If circuit test is normal, replace the radio. |
⇒ | If greater than 10.5 volts, test the signal circuit for a short to voltage.
If the circuit test is normal, replace the radio. |
- Ignition OFF, reconnect the right switch.
- 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, refer to component testing. |
⇒ | If greater than 10.5 volts,
repair the voltage supply circuit for a short to B+. |
- Test for 1-4 volts when pressing the right switch 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, refer to component testing. |
- If circuits test normal, refer to component testing.
Component Testing
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the suspect switch.
- Test the right switch for 2360-2400 ohms of resistance between both remote radio control supply voltage terminals.
⇒ | If the resistance is not between 2360-2400 ohms of resistance, replace the faulty switch. |
- 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. |
- 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 |
Repair Instructions
Important: Always perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Steering Wheel Controls Inoperative Mute
Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit/System Description
The body control module (BCM) supplies voltage to the MUTE switch through the Ignition 1 voltage circuit and monitors the Cellular telephone voice signal circuit. When the switch is pressed the BCM identifies the selection, then sends a serial data message
that is received by the component controlled, activating the feature.
Diagnostic Aids
• | Before diagnosis of the steering wheel control, ensure the primary controls of the associated component is functioning properly. |
• | Pressing and holding the Mute button duplicates pressing the phone icon on the rear view mirror for OnStar ready. |
Reference Information
Schematic Reference
OnStar Schematics
Connector End View Reference
Electrical Information Reference
Circuit/System Testing
Note: It is Recommend that Component Testing is performed before Circuit Testing when diagnosing steering wheel controls.
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the MUTE switch.
- Ignition ON, test for 10-12 volts between the ignition 1 voltage circuit and ground at the switch harness connector.
⇒ | If less than 10 volts, test the voltage circuit for short to ground or open/ high resistance. If circuit test normal and the fuse is open, test the signal circuit for a short to ground. |
- Connect testlamp between the signal circuit and ground at the harness connector. Verify testlamp does not illuminate.
⇒ | If testlamp illuminates, test the signal circuit for short to voltage. If circuit test normal, replace BCM. |
- Test for 10-12 volts between the voltage circuit and the signal circuit at the harness connector.
⇒ | If less than 10 volts, test the signal circuit for an open/high resistance. If the circuit test normal and the fuse is open, test the signal circuit for a short to ground. |
- If all circuits test normal, refer to component testing.
Component Testing
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the MUTE switch.
- Test for infinite resistance between the ignition 1 terminal and the voice signal terminal with the switch in the open position.
⇒ | If less than infinite resistance, replace the switch. |
- Test for 0.2-1.5 ohms of resistance between the voltage terminal and the voice signal terminal with the switch closed.
⇒ | If resistance is not between 0.2-1.5 ohms, replace faulty switch. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.