Currently swapping a 99' Chevy Vortec 5.7L 350 into a 1986 CJ. I am using the stock wiring harness from the cehvy motor. Engine starts and runs no problem. I am having trouble with the charging system. It has an alternator with the internal fan on it. There is one wire that plugs into it and it is brown. I have 4 gauge wire running off the post back to the battery for charging. The question is what do I hook the brown wire up to? I thought switched 12v but it does not activate the alternator to charge. If i do tie into 12v switched then i guess the alternator is bad?? Does this wire need resistance to activate the alternator. Any help is greatly appreciated. Hoping to go to OK next weekend but this is holding me back. I know someone has done this before. Thanks. Chip

Also, if this is not the best place to post let me know. I had it in Chevy forum but had no luck. Oh, and i have searched this and had no luck, thanks, Chip

:confused:

I'm not much help! I'm doing a 98 vortec 350 swap in My wrangler also. I had My harness/ pcm redone at Jim's performance. He left Me a wire hangin out of the harness with a tag on it saying ( excite alternator). He told Me I need to hook it up in the dash, I haven't figured out where yet! Maybe thats what your brown wire is for!

Exactly, I have that same wire to excite the alternator to turn on to charge but dont know what to hook it to. 12v switched? or does it need some kind of resistance like putting a bulb in between? Im lost.

it goes to a fused ign source.

i would just use a underhood relay and fuse triggered by the ign.

OK, I tried that today and had no luck. The alternator might be bad. Ill have it checked and then wire it back up and hopefully that will be the cure. Thanks, Chip

So, pulled the alternator and had it tested, BAD. I was happy to find that was the problem. I hooked up the new alternator adn the brown wire to a 12v ignition and tried it. Alternator worked for about 30 seconds, check output again and now i am back to square one. Any other suggestions on what to do?

Guys I am also in the process of putting a 5.3L in a 88 YJ and I was wondering if you do not mind sharing 2 questions
1: What are you running for a fuel pump (the LS1 has to have 65 LBS fuel pressure

2: The guy that sent his harness out where did you send it and did they do much with it? I am trying to decide if this a good thing to do or just work the wiring my self.

Thank you very much
Darell

Guys I am also in the process of putting a 5.3L in a 88 YJ and I was wondering if you do not mind sharing 2 questions
1: What are you running for a fuel pump (the LS1 has to have 65 LBS fuel pressure

2: The guy that sent his harness out where did you send it and did they do much with it? I am trying to decide if this a good thing to do or just work the wiring my self.

Thank you very much
Darell

I took the fuel pump from the donor truck and put it in my jeep sender. Just switched pumps, they look just about the same! Haven't fired it up yet, hope it works! for The harness, I sent that and My pcm to Jim's performance! He took everything off that I don't need. He reflashed the pcm to delete all the changes and gave it a mild tune! The harness came back (with in a week) all labeled with new wireloom and looks new. It cost Me $450, but I am so glad I did it. I do have some more stuff to do to tie the rest of the jeep wiring together. Jim has been a great source of info!

GOt it worked out thanks for all the help. Went to the parts store and bought a 194 bulb and fixture, wired it up inline, got a new alternator and works like a charm.

I had the harness done at fuel injection specialties and it was worth every penny. Only had to mess with 10 wires and it started right up and runs great. as for the fuel pump i am not really happy with the one i got, it is really loud and annoying. Gonna shop for another.

guys thanks a lot for the feedback, This is alot more complicated than I first thought but I hoping that it will all be worth it. Please keep posting on this link it helps a lot.

Got Mine fired up! I'm a long ways from driveing it, but just hearing it run is a big boost for getting it done. I'm fiddling with hooking up the factory gauges right now.

<a href="http://s397.photobucket.com/albums/pp53/datasara/?action=view&current=fuelpump.jpg" target="_blank"><img src="http://i397.photobucket.com/albums/pp53/datasara/fuelpump.jpg" border="0" alt="Photobucket"></a>I am worried the YJ fuel pump is different so I was going to TJ fuel tank. It has the fuel pump in side the tank. The issue that I just found is that the fuel canister has a fuel regulator built in it. So I am going to have to figure a way to disable the fuel regulator.

The fuel pressure for a LS1 is 56 LBS not 65 like I had stated earlier.

I have done that exact swap with the 99 5.7 into my 86 CJ7. Sent my harness and PCM off to some guy on the east coast. At the time there were very few people cutting down harness'

Man was it a mistake using him. I finally ended up getting a Painless harness and then had to buy a 96 PCM as the Painless harness didn't support the PCM that I had.

I also had the same problem with the alternator. After everything was tried I finally just bought a 1 wire alternator. Haven't had a problem since.

The problem I have had with my fuel pump is that it was mounted on the rail directly in front of the tank. Had never moved the fuel lines.

If I drive it through the desert and get it real hot on a hot day it will vaporlock. Then bought all the stuff to re-run my fuel lines on the outside of the frame rails to reduce the heat saturation and moved the pump into the tank with a V8 grand Cherokee pump. no problems since.

Part of the heat buildup for me was due to the CA smog laws and having to keep the 2 ODBII CATS. Those are next on my list of things to remove. And it is just about time as soon as we get paste TDS Desert Safari.

Finally going to take the time to install all these parts that i have been collecting in the garage.

Good luck with yours.

jsmith, did you put the grand cherokee fuel pump in the stock cj tank? If so what did you have to do to make it fit? What year was GC was the pump for? I have a FI motor and trying to not put in a fuel cell so any help would be appreciated.