If its a factory head unit it probably WILL NOT have a specific remote wire (which is blue as stated). This does not mean you cannot fit an amp though.
A remote output is simply a convinient connection on aftermarket headunits that only gives power when the ignition has turned 1 click or more, and is nearly always 5 volts (check your amp spec).
Turn the key to the first position and use a multimeter to find out which wire on the ISO connector is 5V. Once you have done that then check that when the key is turned to OFF, no reading is given for that wire. This is your wire to tap into (otherwise keep looking).
Connect another wire to this one and run it to your amp. Job done.
Hope this is of some use to you - Laurence.