Wiring my Headunit

Theres the red yellow and black wires.. Blacks ground the other two are 12 volt constant and Acc. If I hook them all up black/black red/red yellow/yellow My headunit turns on than right off. If I hook up both yellows and reds together (all 4 together) My headunit works fine but I shut the car off and lose all of my presets.. Any ideas why it wont work right? Am I missing something stupid here...?

Mazda truck? are you using a plug kit that plugs into the factory wiring harness? Because if you look carefully that black wire doesnt go to a corresponding wire on the truck. You have to screw the black wire down to the body of the truck, where the radio console bracket attaches to the floor is a good place.

The yellow is the constant 12v, the red is the acc. You likely have a blown fuse on the yellow wire, which will make it operate as you describe.

Always always always: check the fuse box.

Well I hooked the black plug wire off the headunit into a black wire that was already bolted to the cab floor . Ill def. Check the fuses though. Thanks

you dont ever have to ground a wire from the headunit to the floor, never...i sell scosche harnesses for all cars you ground right into that harness, its very simple...never waste your time grounding a head unit to the floor

you shouldn't have to ground it to the floor, but we sell metra and best kit harnesses and not all vehicles have a ground in the harness, cause they are chassis ground and just like Russ said you have to ground that wire somewhere, in the dash usually works.

your acc and 12v are backwards test it with a test ligt with the ign. off one will still be on thats your 12v turn on the ign and the other will turn on and just leave the black the way you had it