pac-200, bg12

I plan on installing two batteries in my truck. I've done the research up to installing the BG12. That's whats confusing me at the moment. Install the BG-12 RED = Connect to +12v accessory wire. Hot only in accessory and run position. ORANGE = Connect to +12v dimmer wire. Wire will have +12 volts when parking lights are on. YEL/BLK = Connect to PAC-200 relay coil terminal as shown in diagram below. (either small silver terminal) YELLOW = Connect to +12v Ignition. Hot only in run position and not in accessory position. BLACK = Connect to vehicle’s chassis ground. Do not connect directly to battery post. This is the basic install guide that comes with the module. Now I have a 2002 ford f150 Lightning. I pretty much know where everything goes as far as wiring, but the yellow wire is whats giving me issues. Its looking for a wire that is hot in run position but not accessory. That's where I'm lost. I don't know if my truck has a wire that is hot when running but not in accessory position. I also have a question bout that relay itself. I was wondering if anyone knew if I could mount it closer to the secondary battery. I was trying to keep my engine bay as clean as possible and it says to mount it towards the primary battery. I will be fusing before and after the relay for 0 power surges but will it hurt to mount it closer to the secondary battery because it will be mounted in the bed with the battery. Any info would be awesome.

You can mount the relay anywhere. It's merely the fuses/breakers that must EACH be close to each battery (and btw, they are more for short-circuit protection rather than "surges"). But if you want a typical dual battery isolator, the BG12 is unsuitable. The BG12 is a "battery protector" aka low voltage cut-off to protect batteries from over discharge. A dual-battery isolator is similar but with a higher cutoff voltage - eg, 13.2V. In general, the best dual- or multi-battery controller is a typical alternator's charge light circuit though they may not be able to control big relays like PAC 200s directly - a smaller intermediate/buffer relay else transistor etc may be required.