You've guessed it! Electrical Weirdness...

2006 Freightliner Columbia S60 14.0L
I've had this issue ever since I bought this truck (used). Every now and then while driving I'll hear some high pitched beeping that'll start off slow, speed up, and then I'll lose power to my cigarette lighter. I'll also add interior dome lights (80% sure) to this scenario simply from observational experience (like if my batteries get low) since I'm not exactly opening up my door while driving. Once power is cut the beeping stops and it's some time before power is restored. Once power comes back I usually don't have any more issues for the remaining duration I keep my truck on (or warmed up). And now that it's getting colder it seems to happen more frequently, but I'm unsure if cold temps are related.

I figure that it has to do with a relay; it's the only thing I can think of that'll possibly give off a warning beep. But which relay? I can never pull over in time to catch it while it's going off. While sitting/idling I can't duplicate the problem pulling fuses/breakers. Pulling the 70A ACC relay doesn't do anything. Pulling the cig [breaker] fuse will cut power to it, but I'll still have dome lights. Pulling the dome light fuse won't effect the cig lighter.

If anyone familiar with the wiring in this truck, then can you tell me where and how the cig lighter and dome lights are linked together?

 

WOW....I wasn't even close. I'm glad I decided to ask this forum lol. Can anyone send me a pic of the LVD so that I know what to look for in my search? And is there more than one in this truck?

Oh, and I would replace it rather than bypass it. I figure that it serves a necessary function. Either it's draining my NEW batts or something else is. A related issue is that within the past month (pretty much when the weather got cold consistently) after letting my truck sit for 34hrs the dome lights won't come on when I first get to my truck. Now I know it's because of the LVD.