Mikef714

I just had an Eclipse AVN5500 installed in my 2004 coupe. It works great with the exception of the radio reception, both AM/FM, which is not nearly as good as my original radio. Anyone else experience this with an aftermarket system? Any ideas as to how the reception could be improved? Thanks in advance.

markcz

I have a theory about this, but I still haven't proven it either way...

In C5 coupes there is an antenna module/amplifier under the carpet behind the drivers seat. That module is what the front windshield and rear glass antenna leads connect to. From there it's a single antenna lead that plugs into the stock radio. Click here to see the schematic for the antenna module.

Here's my theory: The antenna module is normally powered by +12VDC supplied from the stock radio through the Dark Green wire, but it is TURNED ON with +5VDC through the Pink wire which is only energized when the stock radio is playing a radio station. Whenever an aftermarket HU is installed in a C5 the +12V Dark Green wire is connected to the new HU's 'antenna power out' wire, but the pink wire that actually turns on the antenna amplifier is never connected to a 5V source, which makes radio signal reception with an aftermarket HU just plain crappy.

I came up with that theory a few months ago when I installed my Kenwood HU. My radio reception is rather poor, however, between the MP3 CD player, Sirius channels 19 & 23, and my 60GB iPod with 14GB of music on it I just haven't been motivated enough to install my 5V power supply to see if it solves my reception problems. I bought a cell phone car charger that has a 5V output, one of these days I'll install it behind the seat by using the green wire at the module as the + source (it's connected to my Kenwood antenna power wire), the module ground wire as the ground, and then splice into the pink wire with the charger output. Theoretically that should give the module both 12V and 5V whenever my new HU is selected to the radio tuner, which theoretically should improve my radio reception.

Anybody tried this yet, or see a reason why it won't work? Maybe I'll try it out this weekend if it's raining on Sunday like they say it will be.

Mikef714

Thanks for the input! I think you have the solution. This may not be feasible, but any thoughts on bypassing the module?
Thanks again

markcz

I wired in my cell phone charger to the antenna module, and it does seem to help, especially on AM. While I was experimenting, with the module OFF and the radio ON, I unplugged the antenna plug that supplies the radio, and reception almost went away completely, so I believe that the module just acts as a fancy "Y" connector for the two antennas if it isn't powered, so attempting to bypass it wouldn't do much good.

The charger I used is a Belkin Mobile Power Cord for Audiovox/Kyocera/LG/Samsung/Sanyo that I got at Wal-Mart. I also used a Car Power Adapter with Battery Clips that I cut the clips off of.

Here are some pics of the module before - during - and after the mod.

For the power plug, I spliced into the green wire for the + cord, and used the grounding bolt just above the module as the ground.

The cell phone charger plugs into the power plug.

I used a multimeter to determine that the red wire at the output of the charger was the +5VDC, then spliced that wire into the pink wire going to the antenna module. I didn't connect the white ground wire to anything, it's just taped up. NOTE: This assumes that nothing is connected to the pink wire at the plug where it went into the original Delco/Bose HU, if you ever reinstall the stock HU this mod must be removed first!

Cover everything important with tape, add a few zip ties, put the car back together, and enjoy your aftermarket radio. Just don't decide to vacuum your carpet afterwards and suck up two of the four seat mounting nuts, the inside of a shop vac can be messy

Mikef714

This is great! Thanks again.

SilverC54me

Markcz

How did you determine that the pink wire is looking for a 5v signal?

Gary

markcz

While I was installing my Kenwood HU I wanted to make sure that everything was connected properly, including the antenna module, so I could get the best reception possible. I have a service manual, which includes this page with the pin-out of the antenna module power plug, and this page with the schematics for the antenna module. Since neither the schematics nor the pin-out has the voltages listed I did some experimenting with a multimeter while my stock HU was still installed.

The results of the experiment....
The dark green wire supplies +12VDC to the module whenever the Delco/Bose HU is on. The pink wire supplies +5VDC to the module whenever the HU is playing a radio staion (as compared to a tape/CD or the Changer). Also FYI, the antenna module is electrically grounded by its mounting screws, there is no ground 'wire'.

I came to the conclusion that the "Radio ON Signal" in the schematic was the 5V signal on the pink wire, and that it was what 'turned on' the amplifier module, which was actually being 'powered' by the 12V wire.

I installed my new HU with the intention of hooking up my antenna module power supply mod the next day, but between the radio reception being 'good enough', and the other source choices besides the radio, I just never got to it until today.

SilverC54me

Thanks for the info. I'll have to work on a circuit to do this.

Gary

Mikef714

I just did this mod and it works great. Thanks to Markcz and this forum.

markcz

SilverC54me

Just did mine yesterday. I added a LM7805 voltage regulator to the antenna module. This provided the 5V to the pink wire.

Best thing the chip is attached to the antenna module.

Gary

Sorry forgot to take pictures.

bomax

Oh sweet. This is cool because with a relay this 5vdc pink wire could be used as a remote turn-on lead for a power antenna, so the antenna only extends when the radio is in use. (Being a Z06 owner, mine did not come this way from the factory.)

2resonate

A much simpler solution than splicing in a cell phone adapter is to go to Radio Shack and buy a $2 voltage regulator part #276-1770.

This IC circuit will reduce the 12 VDC to 5 VDC and is the size of a dime. 5 volts is the standard trigger voltage in car applications. Split the power antenna lead on the aftermarket head unit, attach one lead to the dark green wire in the wire loom, attach the other lead to the IC circuit input, and run the output lead from the IC circuit to the pink wire in the wire loom and it should work just fine. You might want to screw the IC circuit to a piece of metal around the head unit for a heat sink, and shrink tube the power leads to avoid any shorts.

I will try this soon, since I will be changing to an aftermarket head unit, and I can't tell you HOW HAPPY I AM TO HAVE SEEN THIS POST BEFORE I HAD THE PROBLEM!!!!!!!!!!!

boomer 33

Did you give this a try yet?

UR LZN

Careful - it''s not as simple as it sounds!

I just tested the output from the radio to the antenna module. It’s a little tricky!

Connector C1, Pin 8 (dark green) has 12vd on it when the radio is on and 0vdc when the radio is off.
(Simple)
Connector C1, Pin 6 (pink) is switch with the mode of the radio…
Radio off = 0 vdc
CD = 0 vdc
FM = 5 vdc
AM = 0 vdc

SOoo…
The active (amplified) antenna on the C5 is only switched ‘on’ when the radio is in the FM mode!

I haven’t tested the reception either way BUT you may need to switch off the 5vdc when listening to AM (like anyone does THAT anymore!)….

Just my latest investigations....

boomer 33

I got an 07 coupe, reception kicks ***.

LS WON

There is absolutely no information on the C-6 General Discussion (FAQ) the solution to this is different and involves a firmware upgrade.

RainJ

How did this work out for you?

Rain

mperl93

I have an 04 convertible. Does this have the antenna module that needs 5v?

pentavolvo

if u have a power antenna then u are fine and dont need anything special