Car Stereo-Batt Constant (Batt+), Is it supposed to be a 12v signal?

Swapping over a known good stereo from my truck into my car. Got everything hooked up and its a no go. No response from the head unit. Probing the wires, im getting a full 12v (key in acc) and 14v+ (key on) on the ingition wire(red in this case), BUT on the batt+ wire (yellow), im only reading about 1/2v both key acc and key on. Heard the batt+ is just for the radio preset's/clock, so it would make sense to me that it would only need the 1/2v. BUT, the yellow batt+ line says 12v on it.... so i think somewere in there lies the problem.

Thought id doulbe check with someone who might know for sure....

Fuses check out on the stereo itself. There's a 1a and a 15a fues both good. The under dash 10a fuse is fine. Goin to look around at the underhood ones now tho. Will get back to ya on what i find.