Big7 cable kit install question

Khayhur87

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Joined
Oct 10, 2022
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12
Location
Belton, South Carolina
Just bought the Big7 cable kit for my 93 yj. My question is about the existing cable from fuse block to alternator. The new cables come with 150/200 amp inline fuse from battery to alternator. What do I do with the old wires coming from fuse block to alternator? Thanks in advance
 
I just zip tied it out of the way. It is no longer live, but I did not snip it off in case I ever wanted to return to the standard wiring/fuse arrangement. You may also find that the one for the alternator ground to the engine block is too short to use. Overall I have been very happy with the wire set.
 
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I just zip tied it out of the way. It is no longer live, but I did not snip it off in case I ever wanted to return to the standard wiring/fuse arrangement. You may also find that the one for the alternator ground to the engine block is too short to use. Overall I have been very happy with the wire set.
OK. So do I take the fuses out of the fuse box for the alternator?
 
Yes. Are you following the printed instructions? You can also watch the videos at the bottom of the page here:

 
I attached the large replacement fuse provided to the jack location.

457DE903-8854-4217-A598-F0416600C2DE.jpeg
 
I still have the OEM cables on my '92 and was thinking about the internal corrosion on them and replacing them anyhow. I've had several cars and a tractor where the battery cable was down to one corroded strand in a bunch of white powder hidden inside a clean cable shield. You'll never know until you cut it open.

The install looks very straight forward but seems like a lot is bypassed with this new kit.

Question: Currently the red cable from the alternator goes into a big sleeve all the way around to the ECU on the drivers side. So your saying all that gets eliminated by the short cable to the new fuse block? Wow, I'm glad some electrician figured this out.

Since I just have a classic daily driver with LED lights I'm going with the 4ga wires.

Thanks for posting this.
 
I still have the OEM cables on my '92 and was thinking about the internal corrosion on them and replacing them anyhow. I've had several cars and a tractor where the battery cable was down to one corroded strand in a bunch of white powder hidden inside a clean cable shield. You'll never know until you cut it open.

The install looks very straight forward but seems like a lot is bypassed with this new kit.

Question: Currently the red cable from the alternator goes into a big sleeve all the way around to the ECU on the drivers side. So your saying all that gets eliminated by the short cable to the new fuse block? Wow, I'm glad some electrician figured this out.

Since I just have a classic daily driver with LED lights I'm going with the 4ga wires.

Thanks for posting this.
See steps 9-12 through of the instructions for the explanation.
 
See steps 9-12 through of the instructions for the explanation.
Yeah I saw that and followed along to see what they're describing. I'm just saying it's a long way to go from the alternator to other side of the engine compartment the way the factory did.

I'll take another look at it but not that it makes any difference.

Edit. Nevermind,. I looked inside the loom and it's a different wire.
 
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I just zip tied it out of the way. It is no longer live, but I did not snip it off in case I ever wanted to return to the standard wiring/fuse arrangement. You may also find that the one for the alternator ground to the engine block is too short to use. Overall I have been very happy with the wire set.
I cannot find on additional info on that "Alternator to Engine" cable. I understand where it goes, but am I supposed to leave the existing wire attached as well? It seems like it is attached to a black box that has other wires.
 
I cannot find on additional info on that "Alternator to Engine" cable. I understand where it goes, but am I supposed to leave the existing wire attached as well? It seems like it is attached to a black box that has other wires.
Did you get this sorted out? I disconnected it. As mentioned above, I just zip tied it out of the way and left mine attached to the fuse box, in case I want to return things to the stock set up. Part of the install is removing the stock fuse(s), which should make the wire dead.
 
Did you get this sorted out? I disconnected it. As mentioned above, I just zip tied it out of the way and left mine attached to the fuse box, in case I want to return things to the stock set up. Part of the install is removing the stock fuse(s), which should make the wire dead.
Just to be clear...

I had a "Fuse to Alt" (Red) cable, and an "Alt to Block" (black) cable.

For the "Fuse to Alt", I disconnected the existing cable and moved it aside.

The existing "Alt to Block" runs through a black box that has 2 additional cables coming out of it.

This is the cable where I wasn't sure if it was safe to disconnect the wire and zip tie aside.
 
I still have the OEM cables on my '92 and was thinking about the internal corrosion on them and replacing them anyhow. I've had several cars and a tractor where the battery cable was down to one corroded strand in a bunch of white powder hidden inside a clean cable shield. You'll never know until you cut it open.

The install looks very straight forward but seems like a lot is bypassed with this new kit.

Question: Currently the red cable from the alternator goes into a big sleeve all the way around to the ECU on the drivers side. So your saying all that gets eliminated by the short cable to the new fuse block? Wow, I'm glad some electrician figured this out.

Since I just have a classic daily driver with LED lights I'm going with the 4ga wires.

Thanks for posting this.
Old post, but people reviving this thread led me to comment. I think your tracing back to the PCM is incorrect. The alternator power cable is black and gray and switches to red in the harness. It comes out to a plug in connector on the right fender by the PDC. The other side of that connector remains an 8 Gauge and then somwhere between there and the power distribution center near the battery it splits into 2 10 Ga wires and goes to Fuses 2 and 6 in the PDC.

The only ties the alternator has to the PCM are the two operational wires: the field and the exciter wires.

The ground for the alternator is a short cable that ends at a bolt in the engine block by the engine mount bracket.
 
I cannot find on additional info on that "Alternator to Engine" cable. I understand where it goes, but am I supposed to leave the existing wire attached as well? It seems like it is attached to a black box that has other wires.
Just to be clear...

I had a "Fuse to Alt" (Red) cable, and an "Alt to Block" (black) cable.

For the "Fuse to Alt", I disconnected the existing cable and moved it aside.

The existing "Alt to Block" runs through a black box that has 2 additional cables coming out of it.

This is the cable where I wasn't sure if it was safe to disconnect the wire and zip tie aside.
the black box is just a simple little box that holds the ground and the two PCM wires together at the alternator.

Your new "alt to block" can replace/bypass the thick cable in the little black box, all the old cable did was run to the block just the same. The two small wires come from the PCM and remain unchanged: that is how the PCM controls the alternator voltage and how the PCM turns the alternator on.

fuse to alt will be different than stock. Stock is the black 8Ga cable inside the insulator bracket at the top of the alternator, which turns red in the harness and then splits into 2 smaller 10Ga red cables as it enters the stock PDC (black fuse box) and goes to fuses 2 & 6. The new cable will bypass all of that and go straight from the battery to the fuse you install, and then from there to the isolator boot connection at the top of the alternator (where the old cable went).

Removing fuses 2&6 from the PDC makes sure the old wire is dead...if that wire is not dead then you will have a large short when that cable touches metal. Which would inevitably end up popping fuses 2&6 anyways.


Little more info for those interested:

This is C120, the little box referenced in the thread on the alternator. It looks like a scary proprietary connector, but for the most part it's just a little housing to make the connections easy and protected.

1704914069652.png
 
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the black box is just a simple little box that holds the ground and the two PCM wires together at the alternator.

Your new "alt to block" can replace/bypass the thick cable in the little black box, all the old cable did was run to the block just the same. The two small wires come from the PCM and remain unchanged: that is how the PCM controls the alternator voltage and how the PCM turns the alternator on.

fuse to alt will be different than stock. Stock is the black 8Ga cable inside the insulator bracket at the top of the alternator, which turns red in the harness and then splits into 2 smaller 10Ga red cables as it enters the stock PDC (black fuse box) and goes to fuses 2 & 6. The new cable will bypass all of that and go straight from the battery to the fuse you install, and then from there to the isolator boot connection at the top of the alternator (where the old cable went).

Removing fuses 2&6 from the PDC makes sure the old wire is dead...if that wire is not dead then you will have a large short when that cable touches metal. Which would inevitably end up popping fuses 2&6 anyways.
Thanks.

I wasn't sure if removing the original ground wire would interfere with those PCM cables.

That alternator ground cable is the only cable that is not shown in any install video on Youtube.
 
Thanks.

I wasn't sure if removing the original ground wire would interfere with those PCM cables.

That alternator ground cable is the only cable that is not shown in any install video on Youtube.
Nope, should be good to go. I get what you mean, it took me a while to realize what C120 was as well. I eventually learned about it years ago when I think someone like Poweraddicts took his apart or something.

It might be difficult to take the box apart to remove the ground, you might be better off just leaving both of them fastened to the alternator and put the new cable on top and run it to the engine block. In all honesty, your stock ground is likely still fine so unless you just really want to use the cables you bought, you probably don't need to and won't benefit from changing that one out.
 
Nope, should be good to go. I get what you mean, it took me a while to realize what C120 was as well. I eventually learned about it years ago when I think someone like Poweraddicts took his apart or something.

It might be difficult to take the box apart to remove the ground, you might be better off just leaving both of them fastened to the alternator and put the new cable on top and run it to the engine block. In all honesty, your stock ground is likely still fine so unless you just really want to use the cables you bought, you probably don't need to and won't benefit from changing that one out.
I have both ground cables attached right now, but the Jeep is not in use.

I figured it works like you stated, and that the path of least resistance would leverage the new cable.