Please explain factory radio connections

I am wanting to troubleshoot a 1994 Factory CD unit (Infinity model 5269480). I was expecting the placard on the radio to have POS, NEG, ANT, along wiht the speaker connections, but what I find is BATT, ACC, PARK, MUTE, and ILL, along with the speaker connections.

What are these (BATT, ACC, PARK, MUTE)?
ILL and MUTE seem to be pretty explanitory, but the others, I don't know.

I want to know which is positive and negitive so I can power it up.

For those with the question, "what is the problem with the unit", the AM/FM cuts out intermittently when you hit a bump in the road. The CD player works fine all the time. I am expecting that a ground or circuit has a bad solder connection on one of the radio PC boards. I have fixed similar problems like this in the past, just not with these stereo units.

Thanks,

Lon