So the two wires in the ashtray(actually what I meant is the ashtray housing) are indeed both positive and ground. I tested them with a volt meter and they gave off a reading of 12V when i was testing them earlier and getting inconsistent readings it was because I forgot to switch the voltmeter to read DC.

The strange thing is, when you connect a power consumer the voltage drops below operating levels (to 90s) and as soon as you take away the power consumer it goes back up. I had to get an inverter that had the option of connecting clamps directly to the battery terminals and then I ran an extension cord into the cab. worked for the time being.

However I'm wondering why I cant get a consistent output from the ashtray wires. doesn't it simply connect directly to the battery except for the fuse box? or is there some more complicated electronics somewhere linked up to all that?