jvc car radio memory

[siday]

can anyone tell me anything about the memory on the jvc ks-fx722r car radio cassette? There is a permanent live coming through the wiring loom from the car, but the stereo isn't holding it's memory, all the settings reset when you turn the car off and then on again (ignition) I thought it might have a battery inside for the memory, but when i looked there was no battery. Any clues coz i'm stumped