Audio Systems: wiring a car radio into a caravan, car cd player, professional method

Question
I am trying to wire a car cd player into my caravan, someone has obviously done it before as there are the speakers and the cable for the mains but when I tried to do it this evening I could get nothing to work, the player is a new one so it has all the separate wires for speakers and and a host of others, I have tried nearly every combination I can think of and still nothing. Please help.

Answer
You cannot guess at this (and may have already damaged the new deck).
Test the headunit out of the vehicle and if it still works, take it to Circuit City for installation.

DIY:
Basically, you will need to ground the headunit to the vehicle chassis, provide a fused 12 volt constant lead and provide a fused key-switched 12 volt supply (that is a wire which only has 12 volts when the ignition key is ON or in the ACC position).
Look at the back of your speakers to see which color wires are going to them and then use a 9 volt battery up front and have a helper watch the speaker as you quickly tap the 9 volt battery to the speaker leads. IF the speaker 'pops' towards the interior when you 'pop' it, the wire that is on the positive battery terminal is the positive lead to that speaker. If it pops towards the exterior, the wire on the negative battery lead is the positive to that speaker.
Repeat this for each speaker.
This is a professional method for identifying the proper speaker polarity, but no NOT hold the battery on the wires or you may damage the speakers.

Jerry Mael