both batteries are wired in parallel together, or at least they should be, to make one big battery. I'd first start by removing the remote start from the truck and trying to fix the hack wiring job the old owner did to the truck. Disconnect both batteries and charge them, then load test them, if one tests bad replace them both.
Hey guys, I bought my first truck a month ago. Its a 2002 GMC 2500HD LB7 with 175K miles on it. After driving the truck about a week ago, when I parked it in my driveway I noticed that the alarm when the key is in the ignition and the door is open would not go off (I had the key in my pocket), it stayed on for about 15 minutes. I didn't use the truck for a couple days, and the other day I walked by it and I noticed that the clock was on in it. I thought that was weird but didn't think much of it. The other day I went to start up the truck after not driving it for a couple days and it was completley dead. The batteries had gone dead (they are about 10 months old). I looked into it and I noticed that I had a faulty sensor in my ignition that was telling the truck that my key was in it. The previous owner had added remote start to the truck and gotten a new igition. My key says GM so I am guessing it is a GM ignition? Lol. I had a couple questions, first I found a Delco ignition online. It says it is a direct fit into my truck shich it may be. But I was wondering if I would need to change the ignition harness or any wiring it put this new switch in? (I will attach links at the bottom of this). Also are there any tricks you need to do to install this ignition? Also I want to remove the remote start so is there any special way I need to do this? Last but not least lol, the most important question, am I an idiot for considering doing this myself, or is this something I should take to a mechanic? I am not driving the truck daily yet, so there isn't an extreme time crunch for the truck to be up, but I don't want to take on too much, and hurt the truck more then I help. Any help or advice is greatly appreciated, thanks, John