200 Amp Alternator 14v tap

[erasedhammer]

I have recently installed a 200 amp alternator in my humvee in preparation for a 4l80 swap. In the instruction booklet, it says to ground the 14v tap. This makes no sense to me, so why do they do this? Also, if it is never hooked up to anything, what is the point of the dual voltage alternator?

 

[Wire Fox]

That instruction was trash and I see a lot of discussion about it here. If you want to hook it up for proper dual-voltage use, check out TM 9-2320-280-20 Vol 1 and look at section "1-23.2. GENERATING SYSTEM OPERATION (200 AMPERE DUAL VOLTAGE ALTERNATOR)"
It has a simple diagram there to show you the simple layout of how it's supposed to be. It doesn't get tied to ground, it goes instead to a buss bar (technically optional) and to just one battery. There's some more detail in the section that follows.

EDIT: Actually, the follow-on text is in Vol 2 of that TM, 4-5.7. (6.5L) 200 AMPERE DUAL VOLTAGE ALTERNATOR (12447109) REPLACEMENT

 

[Retiredwarhorses]

That 14v tap is run to the positive post on the rear battery for a factory 4L80E equipped truck with TCM.
just leave the ground strap off...it needs a load to produce voltage anyway.