Ok so I've fitted an aux into my radio, plugged it into the back etc that bit is all correct, however now I've plugged my phone into it it doesn't play?!? Is there anything else I may have missed? Thanks in advance for the help.
I have done this. The music doesn't come through. I'm starting to think the aux plug doesn't work. Or its the wrong one. I'll take a picture of the plug.
You have three wires. The red one (usually right one) goes in the middle. The earth wire goes into the one on the right of the red and last but not least thee other one to the left. As shown @ https://www.fiatforum.com/grande-punto-guides/127299-generic-mp3-input-active-hu.html
Best bet is to follow what that guide says for 3.5 mono socket but if want two way to one (rca) follow the first guide I linked to near top of the thread.
What cable did you buy? Has just found a connects2 one (https://www.dynamicsounds.co.uk/connects2-ct29ft01-fiat-all-models-aux-input-interface-adaptor.html
). I would try this before you strip any cables (will need a rca to mono cable). Connects2 usually work great (had steering controls before an no issues)