Headunit wiring issue

[petrolpat]

I just replaced my stock Eurovox stereo with a double din JVC unit and I thought i had followed the wiring diagram and wired it all properly and that stuff, but I just realised that now everytime I turn my car on in the morning my dash computer with petrol used and stuff has been reset!
Does anyone know what causes this and how to fix it??

[Lobster]

Did you run a new ground wire or use an existing one?
Is your stereo keeping it's memory?

[petrolpat]

I used the existing ground wire and yeah my stereo keeps it memory and all that stuff