JeepMoreDoor

We have all heard about this and seen numerous posts about installing a 136 amp alt in an XJ, well, here's another one! I'm just needing to get this straight. I read you can just run a 4 awg wire from the alternator straight to the battery+ WITH an inline fuse. Maybe a 150 amp fuse?

To clarify, doing to modification doesn't mess up anything having to do with the PCM does it? Or the Automatic Shut Down relay?

XJlimitedx99

That's correct, but I would HIGHLY recommend you also do all the other main wires under the hood in 4awg

JeepMoreDoor

I read the alt to battery is one of those wires, then negative to chassis ground. Positive wire too? And anywhere else?

XJlimitedx99

1-Battery+ to PDC
2- battery+ to starter
3- battery+ to alternator
4- battery- to fender-well
5- battery- to engine block
6- engine block to firewall

This is Jon Kelley's works in progress. He is on the forum as "5-90" check out his wiring upgrade. Also, consider doing a 160a grand cherokee alternator and the 1awg wiring upgrade, it's no harder to do than the 136a.

http://www.kelleyswip.com/electric.html

JeepMoreDoor

Thank you for bringing that up! I was considering the higher 160amp because I can across one at the JY. It's in a 98 Ram1500. Then I started thinking if I really needed that much output. I'm not really running anything other than an amp to push a 12" sub and upgraded headlight harness. Is 160amps too much charge for the battery?

XJlimitedx99

I don't believe so at all! And trust me, if you have a sub and some lights, there will be more to come haha. I don't really recommend getting a junkyard alternator because you don't know what kind of condition it's in. Plus, will the ram one fit? I'm not sure. My 136a alternator came out of 99 durango an into my 99 xj. For a 98 and below xj, use a 98 grand cherokee alternator. I THINK the 136a and 160a alternator are the same size or pretty similar, but do some more research on that. I have a writeup for my 136a.

JeepMoreDoor

True about more things will come,I'll put off road lights eventually! According to my research 97-98 ram dakota grand cherokee and 98 durango had the same 136amp. And apparently 136 and 160 are the same size so alls good there. Yeah I'm usually skeptical about buying JY parts but might just take the chance, $24 ain't too bad.

Programbo

I'm in junkyards pretty much every wekend and have been getting parts from them for my vehicles as long as I can remember. Some parts you don't want to get from there and some the new ones aren't much higher than the junkyard ones so go new. But I've always had good luck with alternators from junkyards. Just try and get a fresh one. Some junkyards let their vehicles sit for a long time with the hoods up in all sorts of weather. Luckily the ones around here turn their stuff over pretty fast. The 136amp ones are harder to come by.

JeepMoreDoor

Definitely going to try a JY alternator. I saw a few OEM ones and like you said, hood left up, a little discouraging looking. And a few, what looked like remans.

I'd like to make my own cables, only cuz I enjoy making my own "parts" and cuz I hate waiting for shipping lol. I actually made my headlight harness out of a harbor freight 12awg extension cord and a couple relays. Of course with help from existing wiring diagrams...

investinwaffles

I have had several JY alternators rebuilt by reputable shops. I trust them so much more than a random reman'd alternator put together in Mexico - about 75 to have it fully rebuilt around me, 85 if I want the case painted. Just something to consider.

Also, I would suggest using ring terminal AMG/MEGA fuses as opposed to the scree down car audio type. Increased resistance to vibration and wire corrosion. Just get all of that from 5-90 AKA Kelly's WIP AKA John and save yourself the hassle of doing all the R&D.

EDIT:
As I understand it, the alternator output is dictated by the PCM or something (external from the alternator), so you can put in whatever size alternator you want and the only difference is the max theoretical output of the alternator at ~14.4v. If that is equal to or greater than your ampere load on the system, then you are charging the battery. If not you are basically discharging the battery.
And good quality 0/1 Gauge wire will usually do 300 amps or so FYI. The fuse should never exceed the rating of the wire, so give yourself some overhead on the fuse (meaning run a 175 amp fuse for a 160amp alternator).

Try and find a 160 amp unit, use Google while you are at the lot to find the right unit. A very worthwhile upgrade. My voltmeter never moves, but my lights still dim when I use my turn signals because of the stupidly designed headlight switch in the XJ that a haven't fixed with a relay harness yet.

XJlimitedx99

Well $24 sounds like a deal, even if it does have to be rebuilt you're still in it less than or about the same as a new one. If you want to make your own cables then all the power to ya! I decided to buy 5-90's because they are very high quality cables that are the exact lengths for an XJ with the proper terminals on the ends and the inline use already there. Idk if they make a 175a fuse, so you might just have to go with a 200a. I would contact john about it, even if you don't end up buying from him. He is still very knowledgable and helpful as far as anything electrical goes.

JeepMoreDoor

Those AMG/MEGA fuses are a bit similar to the car audio huh? But the amg are better. Would I be able to get these locally like at a best buy or Home Depot? I suppose the 160a is in for the win. One thing that makes me nervous is I read posts about engine compartments catching fire! I assume wrong wire guage and no fuse. Oh and definitely look at doing the headlight harness upgrade. I chose to make my own because I wanted enough slack to route the wires to my liking, and wanted to use common 5 or 4 pin relays. The putco harness has odd honda relays I believe.
Hopefully it's good and only have to spend the $24! Hopefully. 5-90, is that a part number or name of the store, website? Lol. I was reviewing it and might just consider buying a kit for my '00 as well.

XJlimitedx99

No haha "5-90" is John Kelley's username on this forum, as well as naxja and jeep forum. He is the owner of the Kelley's Works in Progress website