A story in one part, TRS, TRRS, AUX, Bluetooth, and hands-free phone calls in a 2005 car

It turns out if your car radio has a jack in the back to connect a CD
changer or satellite receiver, you can, instead or even in addition to,
connect a device to give you AUX and Bluetooth input, and hands-free
phone calls. Assuming you have a cell phone.

Crutchfiled may have the kit you want, but I got mine, by a different
maker, from GTACarkit.com . They have it versions for lots of makes
and models. I think mostly what differs are the connectors on the end.
And they have detailed videos about how to take apart your dash to get
to the back of the radio.

(In my case, the first time I tried this I had to remove the radio. But
Crutchfield had sent the wrong model. They paid return shipping and
refunded my money promptly. I didn't try again for more years. This
time I was able to reach under and behind the radio and plug in the
cable without removing the radio. )

Everything worked fine from the start, except that the intersting thing
is the AUX cable. It didn't work at all.

Android phone but the same problem exists with iPhones.

After the first cable didnt' work, I tried another and it was fine. It
turned out the first one had TRRS plugs and the second had TRS plugs.
I'd bought one cable when traveling in Europe, at a supermarket I think
but in a section with a bunch of phone accessories, and another one in
the USA from Amazon, and hadn't even noticed they were different. They
were both intended to connect the phone to the car radio. I dont'
remember if they both worked, if I even tried both. Since then the
rental car has changed and the phone has changed.

I was afraid I'd shorted something and burned out the phone's output.
Unlikely with the tiny outputs from a phone, but still.

Anyhow, in practice there can be a big difference between TRS and TRRS.

https://www.quora.com/What-is-the-di...es-and-laptops

https://blog.zzounds.com/2020/05/29/...s-trrs-cables/

This is the one that worked, the TRS:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1



OTOH, if you happen to look at a TRRS cable it may well say "Compatible
with Car.... " but not be in the way you want it to be.