Antenna wiring, why are there 2 wires to the antenna?

Are you sure that you bought one for the right trim level / options of your Prius?

I'm pretty sure that the rooftop "antenna" on my 2010 IV is actually four antennas and at least one preamp: AM/FM, XM, cellular (for Safety Connect), and GPS (also for Safety Connect, separate from the nav GPS antenna, which is under the dash).

You could plug in the one that fits and leave off the one that doesn't, and see what car features stop working.

 

Your profile shows a 2007 Prius. I do not know if it is Base or Touring but they appear to use the same parts with only one cable. Does youe car have the original head unit? Perhaps it had an after market antennt for something else.



from 2007 Toyota Prius Parts - metrotoyotapartsnow.com

 

Your 2010 lists 2 different antennas, depending on options. Neither one are the same as the 2007.

 

Right, I didn't expect my 2010 to match a 2007 in any way, but only to suggest how there might be trim-level variants.

That line drawing of the 2007 seems a little vague about just how that "one cable" looks; the connector end over by the right rear door almost seems to suggest a pair of connectors. That's also what I seem to see in online pictures for that part number:

2007 TOYOTA Prius Rear Roof Mounted Radio Stereo Antenna Holder OEM 86300-47030 | eBay

My experience with Toyota's wiring diagrams is that they, also, are kind of vague about antenna wiring. As opposed to all the 12 volt wiring where you get details of exact connectors and pinouts, for antennas about all you seem to get is a line pointing out of the radio drawing and labeled "antenna". You get to figure out the rest by unplugging things one at a time to see what you stop receiving.

 

Betting that smaller, non-coax wire is power for the antenna preamp built into the base.

 

Where did you buy the replacement antenna without the extra wire?

 

Well at least you can still use the antenna form your eBay buy. 5 bucks isn’t a bad price for a replacement antenna.