BMW E60 remote only works up close and the radio cuts out
Why does the BMW E60/E61 remote only work up close and the radio cut out?
The most common cause is an antenna amplifier that has got moisture in it. The circuit board and connectors oxidise, and reception weakens for both the radio and the key. On the E60 the amplifier is behind the high-mounted brake light under the headliner, on the E61 under the tailgate spoiler.
What else should I check before replacing the amplifier?
Check the antenna amplifier fuse (number 77, or 59 in later cars), the ground connection and the wires running through the tailgate hinges. The amplifier connector should have these voltages: pin 1 12 V, pin 2 5 V and pin 3 12 V. If everything is fine and the key only works right next to the amplifier, the amplifier is probably faulty.
Can the fault be in the key or caused by a window replacement?
Yes. The battery of a key that has not been used for a long time can be flat, and with a working key the range is about 50 m. If the symptoms started after the rear window was replaced, the rear window antenna wire may have been damaged.