I'm brand-new to RVs. I just picked up this 88 with only 40,000 miles on it. I'm having an issue with the second battery. As in it's not there! The set up is draining the main battery. I went to look where the second battery should be and didn't see any normal battery terminals. I did see an empty wiring harness socket. Is this what the second battery plugs into and if so where can I get the cable to plug in to the wiring harness? I'll attach a picture as soon as I figure out how to shrink it down to 350 K