For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### 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.

### Diagnostic Aids

• | 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 voltage connection at the right switch could cause all the switches to be inoperative or malfunction.

### Reference Information

#### Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

#### Connector End View Reference

• | Secondary/Configurable Control Connector End Views

• | Entertainment/Communication Connector End Views

#### Description and Operation

Steering Wheel Controls Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

Important: It is recommended 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 right steering wheel control switch.
2. Ignition ON, Radio ON, test for 8.5-10.5 volts between the 10-volt reference circuit terminal 1 and ground.

⇒ | If less than the specified value, test the 10-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.

⇒ | If greater than the specified value, test the 10-volt reference for a short to voltage. If the circuit tests normal, replace the radio.

3. Test for 8.5-10.5 volts between the 10-volt reference circuit terminal 1 and signal circuit terminal 4.

⇒ | 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. Install a 3A fused jumper wire between the 10-volt reference circuit terminal 1 and the signal circuit terminal 5.
5. Disconnect the harness connector at left steering wheel control switch.
6. Test for 8.5-10.5 volts between the signal circuit terminal 1 and ground.

⇒ | If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.

⇒ | If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.

7. Test for 8.5-10.5 volts between the signal circuit terminal 1and the signal circuit terminal 4.

⇒ | If less than the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the radio.

⇒ | If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.

8. Ignition OFF, disconnect the C1 harness connector at the radio.
9. Test for infinite resistance between the signal circuit terminal 11 and ground.

⇒ | If less than the specified value, test the signal circuit for a short to ground.

10. If all circuits test normal, test or replace switch.

### Component Testing

Caution: Refer to SIR Caution in the Preface section.

1. Ignition OFF, disconnect the harness connector at the right steering wheel control switch.
2. Test for less than 2400 ohms of resistance between the signal circuit terminal 5 the 10-volt reference terminal 1.

⇒ | If greater than the specified value, replace the steering wheel control switch.

3. Test for infinite resistance between the signal circuit terminal 4 and the10-volt reference circuit terminal 1 with the switch in the open position.

⇒ | If not the specified value, replace the steering wheel control switch.

4. Test for less than 2400 ohms of resistance between the signal circuit terminal 4 and the 10-volt reference circuit terminal 1 with the switch in the closed position.

⇒ | If greater than the specified value, replace the right steering wheel control switch.

5. Disconnect the harness connector at the left steering wheel control switch.
6. Test for infinite resistance between the signal terminal 1 and the signal terminal 4 with the switch in the open position.

⇒ | If not the specified value, replace the steering wheel control switch.

7. Test for less than 12000 ohms of resistance between the signal terminal 4 and the signal terminal 1 with the switch in the closed position.

⇒ | If greater than the specified value, replace the steering wheel control switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Steering Wheel Control Switch Assembly Replacement

• | Control Module References