You can test to see if things are hooked up with a volt meter - measure the voltage between the charge connector pin and ground pin on the 7-way connector (see
http://www.etrailer.com/faq-wiring.aspx to determine which pin it is), on the vehicle (no trailer plugged in).
An alternative way of testing to see if you have 12 volt power is to unplug your TM from shore power, pull the 30 amp fuse at your TM battery, and then plug your TM into your tow vehicle. If you can turn on the light at the front of the TM (the one with the switch) or the one by the water heater (which also has a switch), you have the necessary fuses and relays. Your vehicle may need to be "on" to do this test (I'd recommend having the engine running so you don't drain your battery in your tow vehicle).
For my Ford, it came set up with the necessary fuses/relays, and I didn't have to do anything - I have 12 volt power when the key is "on", nothing when it is off.