Add Aux-In to Stock C5 Sound System Using an FM Modulator

Using an FM Modulator to provide an AUX-in to the Standard C5 Coupe
Audio System.

Disclaimer: Use these instructions at your
own risk. This procedure worked fine for me but neither I nor can be held responsible for any damage you or your Vette
incur when attempting the same.

These instructions should work
fine for a 2002 C5 Coupe, I�m told the Z06, FRC and Convertible are
different on the antenna front. I believe all C5 coupes are the same for
the purpose of this install.
You will need an FM modulator, I got
one from

will also need some conversion cables as the antenna connectors (Motorola
type?) on the modulator differ to those in the Delco system (Mini-Delco?).
I got the connectors at SoundDomain:


Antenna Adapter

We will be hooking the modulator into the antenna at the
Coupe�s Radio Antenna Module (diversity tuning multiplexer box, referred
to as the Ram from now on) as it easier to get to than the antenna
connector behind the head unit. The RAM is at the bottom of the left hand
�B� pillar, just behind and to the left of the drivers

Connector to the Radio Antenna Module.
2) Coax cable to the
3) Front Body Harness.
4) Coax cable from the
Windshield Antenna.
5) Radio Antenna Module.
6) Coax cable
to the Antenna Buffer

that the drivers seat (A) needs to moved as far forward as possible. I
used a bungee cord to keep it out of the way. To get to the antenna
module we pop off the panel covering the door threshold (B) by simply
pulling up on it. Pull up on the end towards the back of the car first
and then pull the panel back away from the foot well to remove it. It is
attached with reusable connectors. Then pop off the cover over the
seatbelts. Same connectors. Pulling off this cover is more difficult as
the seat/rails get in the way. The RAM is just above the seatbelt reel
mounted on the floor.
[I]This might sound obvious, but it�s an
important disclaimer: Do not have the radio turned on, in fact as we�re
doing electrical work disconnecting the battery might be a good

can use the green wire in the Connector to the RAM(1) for power, it�s only
hot when the radio is on. Loosen the grounding nut just above the RAM and
wrap the black wire (ground) from the modulator and re-tighten, the earth
from the RAM is already connected there. Splice the red wire from the
modulator to the green wire in the connector to the RAM. Now the
modulator has power. Plug the antenna converters into the modulator
antenna connectors. The leads into the RAM are marked “Front” “Rear” and
“Radio”, you can see the front �radio� connection in the picture to the
left. Unplug the coax cable to the Radio (2) and plug the input to the
modulator to the RAM and connect the coax cable to the Radio to the output
of the modulator.
Now all the connections are complete, tuck the
cables away. Replace the �B� pillar cover (which is more difficult than
taking it off) and Velcro the modulator under the vertical carpet behind
the drivers seat.
Then all you need to do is run the audio cable
from the RCA audio sockets on the modulator to your audio device and
reconnect the battery (assuming you disconnected it).
Turn on the
radio, plug in your audio device and hit play. Choose an FM channel and
hit scan. The FM modulator should have isolated the signal to one of 3
selectable frequencies. Store this channel setting and select this
channel whenever you want to listen to your audio device.
background hiss is possible, selecting a different FM channel or moving
the antenna/power wires might help.