Hi, Ive just bought a 99 t plate vectra sri 140, am very impressed with it overall, when i put my stereo from my previous car in it powers on and plays but the setting dont stay in the memory, ive wired it in by plugging in the ISO connectors so am not sure which is the constant power lead to plug it in, the lead on the head unit is yellow but cant find a yellow lead coming from the iso plug. PLEASE HELP!!!!