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Discussion Starter · #1 ·
I recently replaced the touchscreen head unit in my 2011 smart Fortwo Passion with an aftermarket one but I was just wondering what this wire is for? I can't find anything that doesn't work with it not being plugged in:
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It was plugged into this connector on the old head unit:
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The wire goes into the main wire bundle along with just about everything else:
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Discussion Starter · #5 ·
Yep, definitely the antenna
But the radio works, the antenna was plugged into another connector as shown below. Is it possible the the AM band is on a different wire than the FM? As my new head unit doesn't support AM, I could not notice if it is working or not.
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But the radio works, the antenna was plugged into another connector as shown below. Is it possible the the AM band is on a different wire than the FM? As my new head unit doesn't support AM, I could not notice if it is working or not.
View attachment 67865
Not likely. I don’t recall ever seeing a car stereo with separate AM and FM antennas.

If your local signals are strong enough, your radio will pick them up, even without an antenna, but if you get any substantial distance between you and the transmission, the reception will fall off dramatically.

The other connector on the radio is likely for GPS.

What’s the model of the radio you are installing?
 

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I take it the radio on the picture is a factory nav Bosch high line stereo. I’m pretty positive that the connector you asked about originally is for antenna that Is on your left outside the car. It was plugged in the white connector in the back of the unit. Blue connector is a GPS antenna for the Nav. Pink - aux usb cable. If your new stereo has an antenna input (it should) you’ll most likely will need an aspire for it.
 

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What is your new unit brand/model? Any pictures, front and back?
Just curious.
Your radio works without an antenna is probably because you have some strong signals where you are.
I’m pretty sure you’re not getting all the stations, and quality of some will improve with the antenna in.
 

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It's the antenna cable judging from the connector color (just looked at mine a few hours ago). You need an ISO/DIN adapter. I bought mine from Crutchfield.
 

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Discussion Starter · #12 ·
Here are some more pictures of my new head unit. The wire can't possibly be the antenna because the new head unit came with an adapter that plugged into the other blue wire as discussed and it plugs into a connector clearly labeled "ANT". I also tried unplugging this wire and yes, the radio no longer picks up any signal so there is no doubt. The new head unit also came with a GPS receiver and it's plugged into another clearly marked connector.
Here is the link to where I bought my new head unit: 117.99US $ 50% OFF|Android 10 Car Radio Video Player For Mercedes Benz Smart Fortwo 2011 2015 Auto Multimedia GPS Stereo DSP Carplay 4G No 2din DVD|Car Multimedia Player| - AliExpress

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The connector you are asking about is connected to the antenna sticking out of the side of the car. There is no doubt about that. Whatever stereo you are using most likely got the cables wrong and you connected the radio to the gps antenna. Whatever is in place of the gps connector is something else entirely. I see from the AliExpress page you linked that they include connectors for the gps, 4G, and antenna. I am very willing to bet that the stereo you bought just has an adapter for an ISO to (what is very likely) the gps antenna. That blue cable is very likely to be a special connector that Smart used on the OEM stereos and nobody had needed anything like that except in cheap, mass-produced, android stereos (usually bought on Amazon or AliExpress). You don't really need gps if you are using your phone in any way, so the blue cable is essentially useless aside from being a (most likely) hidden antenna working at shorter ranges.

Source: The Antenna is a DIN connector and multiple companies have already created DIN/ISO adapters, as many cars have done this before. If you want to try it, buy one of those adapters and plug it into the antenna port. Chances are it will fit perfectly and will connect the actual antenna to the stereo. Your radio will still work even with the gps antenna connected to it as they most likely work in the same way.

I sincerely apologize if this came off as harsh, it's just you are asking a question that was solved in the first few replies, and refusing that they are right.
 

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I second that. You have your existing Smart GPS antenna connected via that adapter to the Aerial antenna input. That explains why you’re getting some radio channels. You need the DIN/ISO adapter for your antenna (the wire you were asking). You can use your new GPS antenna, or if you want to reuse your original wire from Smart (blue) - there is an adapter for that too.
 

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Discussion Starter · #15 ·
Thanks for all the information people, much appreciated. I just didn't figure that the radio would still work as good as it does plugged into the GPS antenna haha
 
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