not a mopar

Your readings sound normal. Plug a voltmeter into the cigarette lighter. I bought several from Harbor Freight at $3 ea (LED lights) that I use in my modern cars that have poor diagnostics. Don't leave it in an unswitched outlet or may run down your battery. I suspect that your "ALT" lamp is really a "low battery voltage" light. Try to measure exactly the same 2 wires that it monitors. My guess is that it has a bad ground. If you want to avoid getting stranded somewhere, look at the Battery Brain. I have one in most of my cars and has saved me several times.