Audio Systems: cd problems, radio harness, cable side

Question
I have just bought a car and the cd player is brilliant, problem is, it only works when the engine is switched off.  Please help, any advice would be appreciated

Answer
Hi There,
Usual problem is the two power wires to the radio, possitive and accossory get swapped over. The radio needs both to work. pull the radio and check the wire with 12 volts with ignition OFF is going to the power or mem connection and then with the ignition ON check 12 volts to the acc wire.
below is the standard ISO DIN connections that should be on your radio harness.

DIN connections  are.
Speakers
Right rear -,  right front -,   left front -,  left rear-,
Right rear +, Right front +, left front +, left rear +

Power block viewed from cable side

Phone mute (white),/   n/c, /      ariel & amp (blue), /ignition (red)

N/c, / 12vlive, (yellow or orange), / lights, (various colours),/ negative (black)

The third, usually top, block is for accessories such as cd changers