Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit/System Description
The radio (U2R or U2S) or CD changer (U2V or U2X), 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 selection 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. |
| • | If the vehicle is equipped with RPO U2R or U2S, the steering wheel controls are connected to the radio. |
| • | If the vehicle is not equipped with RPO U2V or U2X, the steering wheel controls are connected to the CD changer, which is a serviceable component of the navigation radio. |
| • | Review schematic when testing switch resistance values. |
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 be performed before Circuit Testing when diagnosing steering wheel controls.
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connectors at the left and right steering wheel control switches.
- Ignition ON, Radio ON, test for 9-12 volts between the supply voltage circuit and ground at the harness connector.
| ⇒ | If less than 9 volts, test the voltage circuit for short to ground or open/high resistance. If circuit test normal. Replace the appropriate radio, or CD changer. |
- Test for 0-0.5 volt between ground and toggle to the signal circuit and at the left and right harness connectors.
| ⇒ | If greater than 0.5 volt, test the left and right signal circuits for a short to voltage. If circuit test normal, replace the appropriate radio, or CD changer. |
- Ignition ON, radio ON, test for 9-12 volts between the supply voltage circuit and toggle to the signal circuit at the left and right harness connectors.
| ⇒ | If less than 9.0 volts test the signal circuit for an open/high resistance. If circuit test normal, replace the appropriate radio, or CD changer. |
- Ignition OFF, reconnect the left switch.
- Ignition ON, test for 9-12 volts between the supply voltage circuit to the right switch and ground at the right switch harness connector.
| ⇒ | If less than 9.0 volts test the voltage circuit for a short to ground or open/high resistance. If circuit test normal, refer to component testing. |
- Test for 1-4 volts when pressing the left switch, between the signal circuit and ground at the right switch harness connector.
| ⇒ | If less than 1-volt, test the signal circuit for a short to ground. If circuit test normal, refer to component testing. |
- If circuit test normal, test or replace switch.
Component Testing
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the suspect switch.
- Test the left switch for 2360-2400 ohms of resistance between the supply voltage terminal and the supply voltage terminal for the right switch.
| ⇒ | If the resistance is not between 2360-2400 ohms, 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
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
