No power period. Weird electrical issue. Need ideas on where to start.

This morning I went to start my xj, jumped in and all the light lit up.. turned the key heard a POP then the entire jeep went dead. It's not getting any power anywhere. The taillights don't light up when I hit the breaks, and I can't shift it out of park. A couple things I think are important:

4 days ago I got a check gauges light and noticed the battery was maxed at 19. This happened two days in a row for roughly 4 minutes (as long as it took me to get off the highway), stopped.. then today its dead.

Yesterday I got the alternator, starter, and battery tested. All 3 tested at 100%.

She is fairly dirty, and it's been particularly cold here. I plan on starting with fuses and battery terminals.. but if anyone could point me in a better direction I'd appreciate it. I'm new to the electrical system.

What year?

2001. Sorry meant to put rather in the posting!

Battery terminals sound like a really good starting point, particularly if you have not done a proper upgrade on that front. If you have the typical auto parts store replacement clamps on the end of old factory cables then it is highly likely that is where your problem lies.

I'm fairly certain they are oem (not much of the jeep is but most of my problem spots are). I'll give them a good cleaning and check the connection tomorrow. Is there a brand I should look for when replacing?

The originals were probably at the end of their life ten years ago, unless your Jeep was taken care of better than the typical XJ. In addition to cleaning up the contact areas (insides of the clamps, outsides of the battery posts) pay close attention to where the cable goes into the clamp. If corrosion has set in on the back side of the clamp then the clamp is finished.

My preference for replacement is the military style clamp. The military clamps use a lug connection to the cable. This makes it easier to replace either clamps or cables when one or the other gets damaged. It also makes it easier to add in accesory circuits. You can also get protective boots for the military clamps.

Included in this thread are some pictures of the military clamps: https://www.naxja.org/forum/showthread.php?t=1108471

The other thing to do is to pay attention to the other end of the cables too. Make sure your ground cable has a good connection to the block. There is probably also a ground wire that goes to the fender or radiator support--check that connection. Check your positive cable connection to the starter solenoid. Check your positive connection to the PDC (underhood fuse box). And check the large wire that runs from the PDC to the alternator. Note that last one probably has a section of fusible link in it. Those fusible links can mess you up if you don't know about them. I swapped mine out for a fuse--much simpler to deal with on the trail should the need arise.

If you get all of those taken care of and still don't seem to have power then it will be time to get out a multimeter (or at least a test light) and figure out where you do and don't have power.

Thanks for the info! I'd like to believe she was taken better care of than normal. The guy I bought her off of talked a big game, but everytime I dig into his work I wonder.

I have a buddy coming over today and the plan is to do as thorough a inspection as possible. I was aware of the fusible links.. and concerned since I saw those voltage jumps. Forgive my ignorance here, but when your swapping links for fuses is it as protective? I love the idea of easier trail fixes.

It goes both ways, try to find a current rating on fusible links. Fuses work only if you the right type and amperage.

What fusible links have going for them is a slow blow. They will tolerate a higher current for a period of time. This is needed for the alternator to deal with short bursts of higher current.

My choice is to upsize the wiring and run a larger fuse. I know the bean counters would not do this because of the cost of materials. I am comfortable with my decision, but others may not be.

Fusible links are "Engineered" but a "general rule of thumb" is 4 sizes smaller than the wire your protecting.