No. I've never heard of an amp that grounds positive. Your amp should have a 12v+, a ground (also sometimes called 12-), a 12v+ switched(that usually comes from the deck), and the low voltage audio line ins.
Usually, if your amp isn't grounded, than nothing should happen. Not even a red light. If it's getting a partial ground, this could be happening.
Your frame should be grounded (ie, connected to the 12v- on the battery), and typically you can just run a ground line to a metal ***** that goes into the frame(or use an existing *****). Make sure it's an unpainted ****** and preferably into an unpainted section of the frame, or else the paint will insulate the wire.(you can scrape off the paint where the ***** goes in with a little wire brush to ensure a good connecion and to make sure there's no rust on the ***** or frame) If for some reason, that's not working, maybe the frame isn't grounded for some reason. Try running a test line directly to your battery -. If it still doesn't work, and you're sure your test line is connected properly, then it's either your 12v+, or switched lines, and those should be checked.
What I suspect is really happening, though, is that the red light means that your speaker lines (from the amp to the speakers) are shorting out somewhere. Check these. Make sure they are not shoring out on each other, or shorting out on the frame, or anything. Also, try having them plugged in one at a time, and see if the problem is related to a specific one.
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