B11AF — Entertainment and entertainment module - mobile phone button

Causes

• Faulty mobile phone / hands‑free button (mechanical or electrical failure)
• Damaged wiring or connector (open, short to ground, short to battery, corrosion)
• Poor ground or power supply to the entertainment module or button circuit
• Intermittent or lost CAN/bus communication to the infotainment/phone module
• Software fault in the entertainment module or module needs reprogramming
• Moisture/contamination in the switch assembly or connector

Symptoms

• Phone/hands‑free button does not respond or does not initiate calls
• No hands‑free phone menu or voice call activation from the button
• Intermittent operation of phone controls
• Warning or message on infotainment display indicating button fault
• Possible other infotainment features affected if communication fault exists

What to check

• Read DTCs and freeze frame data with a factory‑level diagnostic tool; note related U‑codes or body module faults
• Visually inspect button, bezel and connector for damage, corrosion or contamination
• Check relevant fuses and battery voltage at the infotainment/module power input
• Backprobe button connector and measure continuity/voltage while actuating the button
• Inspect wiring harness for chafing, bends, or previous repair sections
• Scan CAN/bus activity for errors or lost messages while pressing the button

Signal parameters

• Switch behavior: closed (continuity) when pressed, open when released — expect near 0 Ω when closed
• Supply voltage: nominal 12 V (vehicle battery) to module; expected stable supply (≈11–14 V)
• Logic/line levels vary by design; if button is read via micro input expect pull‑up/pull‑down behaviour (voltage change when pressed)
• CAN bus idle differential voltages ≈2.5 V per line, differential ~0 V when idle; messages present when button pressed (vehicle specific IDs)
• Resistance checks: no high resistance or intermittent change when actuating the button

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