Sirius Satellite Radio Xpress RCi User Manual page 51

If the signal reception is good, but there is no audio when tuned to channel
1, verify that XpressRCi's FM Transmitter is On (step 6), and that both the FM
Transmitter and your vehicle's FM radio are tuned to the same FM channel
(steps 5 & 7). Also ensure the chosen FM channel is a suitable one to use in
your area (step 5). Verify that nothing is plugged into the AUDIO connector
on the
PowerConnect
Vehicle Dock. Refer to "Troubleshooting" on page 110 for
additional help.
Option 4: FM Direct Adapter (FMDA) Installation
The FMDA needs to be installed by a professional installer. Professional
installation can help improve your radio's reception and significantly reduce
the visibility of wires. To learn more, check with the retailer where you bought
your radio, or go to xmradio.com/accessories.