1. Remove the radio. Use a multi meter to measure the resistance between terminals C11 & C12 in the X1 connector; when no buttons are depressed the resistance should be approximately 3674 ohms.
2. When each of the following switches are depressed the resistance measured should be approximately as listed below.
Next up button 794 ohms
Mute button 284 ohms
Next down button 464 ohms
Volume up button 164 ohms
Mode button 1474 ohms
Volume down button 82 ohms
3. If a high resistance is detected, disconnect all connections, inspect for damage or corrosion, reconnect and measure the resistance again. If the resistance has changed and the correct function of the radio remote switches is achieved then the problem is
considered to be connection related.
4. If the fault is still present, use the wiring diagrams, check each section of the circuit separately (wiring harness, clock spring, radio remote switches) to allow diagnosis of the faulty component. .