Or maybe your Mic isn't working or connected properly! If you Nav loom has the blue connector for the separate voice control module that normally bolts beneath the Nav computer then yes you would need the SES jumper plug as this completes the wiring circuit!

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Range Rover 4.4i V8 Vogue on Gas! BMW Mk4 Dvd Nav, BMW Bluetooth,
Aux Input, Digital Hybrid Tv Tuner, Dvd Changer & Headrest Screens