whitels

I bought from eBay a Denon mobile stereo amp DCA-3250. The amp has line level inputs. There are two fuses, 3 amp for ACC and 20 amp for CATT. There are four wires feeding the amp:

Thick Yellow Wire= (I think this is the POSITIVE +12V)
Thick Black Wire= (I think this is the NEG -12V)
Thin Red Wire = I don't know...
Thin Purple Wire= I don't know...

I suspect that one or both of the thin wires have something to do with remote turn on but I'm not sure. The two wires are crimped together with a female spade lug.

Would someone please take a shot as to what exactly those wires are?