Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit/System Description
The radio supplies voltage to the 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 switch selected to activate the feature, otherwise sends a serial data message received by the controlled component activating the feature.
Diagnostic Aids
| • | Before diagnosis of the steering wheel controls, ensure the primary controls of the associated component are functioning properly. |
| • | Review 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 all the switches to be inoperative. |
Reference Information
Schematic Reference
Steering Wheel Schematics
Connector End View Reference
Entertainment Connector End Views
Electrical Information Reference
Circuit/System Testing
Caution: Refer to SIR Caution in the Preface section.
Important: It is recommended that Component Testing be performed before Circuit Testing when diagnosing steering wheel controls.
- Ignition OFF, disconnect the harness connector at the left and right steering wheel control switches.
- Ignition ON, Radio ON, test for 6.5-9 volts between the voltage circuit and ground at the right switch harness connector.
| ⇒ | If less than 6.5 volts, test the voltage circuit for short to ground or open/high resistance. If circuit tests normal, replace the radio. |
| ⇒ | If greater than 9 volts, test the voltage circuit for short
to voltage. If circuit tests normal, replace the radio. |
- Test for 6.5-9 volts from the voltage circuit and toggle to the signal circuits at the left and right switch harness connectors.
| ⇒ | If less than 6.5 volts, test the signal circuit for an open/high resistance. If circuit tests normal, replace the radio. |
| ⇒ | If greater than 9 volts, test the signal circuit for short to voltage. If
circuit tests normal, replace the radio. |
- Ignition OFF, reconnect the right switch.
- Ignition ON, Radio ON, test for 6.5-9 volts between the voltage circuit and the left switch and ground at the left switch harness connector.
| ⇒ | If less than 6.5 volts, test the voltage circuit to the left switch for a short to ground or open/high resistance. If the circuit tests normal, refer to component testing. |
| ⇒ | If greater than 9 volts,
test the voltage supply circuit for the left switch for a short to B+. |
- Pressing the right switch, test for 1-5 volts 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 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 steering wheel control switches.
- Test the right switch for 2360-2400 ohms of resistance between the voltage terminal and the terminal supplying voltage for the left switch.
| ⇒ | If the resistance is not between 2360-2400 ohms, replace the faulty switch. |
- Test for infinite resistance between the 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 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
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
