I've been following the photo cable replacement guide on this forum to replace the cable batteries on a 98 ZJ. I'm on the step for the negative cable from the engine mount to the terminal and I've run into an unexpected issue.

It looks like the voltage regulator from the alternator has been spliced into the negative cable. That wasn't mentioned in the guide so I assume that isn't normal. I already have cables for the battery, but wasn't expecting this. I'd rather not splice anything. Where should this wire normally go? Can it go to any ground location? If so, I guess I'll just clamp on a ring terminal. I don't know how I'd get it all the way up to the negative terminal.

Attached (I think, I'm new here) is an image from google of the wire from the alternator. Mine is still attached, obviously. Its all one piece.

 

Your post is hard to follow because you say 'the voltage regulator from the alternator'. There is no voltage regulator inside or outside the alternator. The voltage regulator is contained in the PCM.
Do you mean something else than what you said?
I think the black wire in the hand pictured goes to a post on the engine block by the coil.

 

Hmm, admittedly I have no idea what the black box is. There aren't any schematics or guides that I've seen that show it. I stumbled upon a couple jeep forums and mostly dodge forums that mention it for unrelated problems (hence where I found the picture), but I do not know if they are accurate either. Does anyone know what the black box attached to the alternator is?

Anyways, I figured it out. I had to cut it and splice a new 8 ga wire to the negative terminal. It seems to be working.

Here are a couple other figures I stumbled upon that show it:

 

That black box is nothing more than part of the connection harness. It's where the wires break out of the cable assemble to the terminals to mount to the alternator the way jeep wants them to.
No electronics in there.

 

Ok, so does it always end up at the negative battery terminal? I haven't seen it on any wiring diagrams before, but then again I don't have any real official sources - any suggestions?Wwould this be in a haynes manual?

Any idea what part it is? Seems like I should be able to buy one that has a cable long enough to reach the batter terminal if thats where its supposed to go.

 

If I understand, you need to know where the wires go? Without looking at the wiring diagram in the service manual, I would say generally, the two smaller wires go to the field, the two little nuts on the back of the alternator. Either one can go to either side, no special way. The black one yes is ground and ground is ground the world around, so take it to the block or the battery but make sure the battery is also grounded with a big wire to the block.
Then there is the red one, this should go to....um.....I would guess the + of the battery.
You can go to the electrical aisle of home depot and find a 'split bolt' connector or two, and buy some thick copper wire like THHN there too and splice it up yourself. Then buy a roll of rubber (not vinyl) tape there also and wrap em up tight.

 

It is an external voltage regulator. I have one on my 92 YJ.

 

You replied to a 5 year old thread, but I nonetheless beg to differ. The VR on his 98 ZJ is not an external regulator unless he has modified it like you and I have.
** 2 years later I realized my mistake here, yes, the factory regulator is 'external' in that it's in the PCM/.
I must have had a moment.