radio memory loss?

hi. i have a jvc KD-G11 radio which i have tried to put into a fiat doblo, but when turning on the iginition the memory of the radio goes, ie stations etc. also, the radio won't turn on at all when the ignition is turned off completely, but it did in my old car (punto). i've taken it out to see about swapping a yellow and a red cable that supposedly solves the problem but there's no way to do this without yanking the seperate coloured cables out of the iso connectors, potentially fatal i would presume. anyone got any ideas? cheers