Coil pack

Coil packs are used on engines that do not use a distributor. You have just a single ignition coil.

For the alternator, you have to determine if you have a failed charging system or a drain on the battery. The two are not the same. The fastest way to find out if the charging system is working is to measure the battery's voltage while the engine is running. It must be between 13.75 and 14.75 volts. If that is what you find, replacing the alternator will not solve a drain. Check out this article for more information:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

This article will help with a battery drain:

https://www.2carpros.com/articles/car-battery-dead-overnight

If you drove for five hours, the alternator is working. With a dead charging system, starting out with a good, fully-charged battery, it would run dead in less than an hour from running the electric fuel pump, heater fan, ignition system, injectors, etc. If the lights were on, the battery would run dead in less than a half hour.

The vehicle should be able to sit for more than three days, then still start, but be aware there is a normal drain on the battery to keep the memories alive in multiple computers. Unless specified differently by the manufacturer, the industry standard is a maximum of 35 milliamps, (0.035 amp), is allowable. Chrysler says at that rate, a good, fully-charged battery will still be strong enough to crank an engine fast enough to start after sitting for three weeks. My 1993 Dynasty has gone six weeks and started okay, but that does not mean every vehicle will start. I have a 2014 Ram truck that also sits for up to two months, and it too will start, but regardless, three weeks is the expectation.

Here is an article about testing fuses:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

You will find many more dandy articles here:

https://www.2carpros.com/articles

Rather than trying to list all the things to check for the drain, start with this article:

https://www.2carpros.com/articles/car-battery-dead-overnight

Then come back and tell me what you found out. I can describe how to use an amp meter to look for the drain, but it is more involved than just connecting it and reading the numbers, like we could do on older cars.

You missed the important part of my story. If the alternator is not working, the most you will be able to drive is up to one hour, if you are lucky. Nothing you have shared so far indicates there is anything wrong with the alternator.

I will be back tomorrow to see how you are doing.

Yes. The alternator recharges the battery after it cranked the engine to start it, then it runs the entire electrical system while you are driving. On today's vehicles that can take 25 to 30 amps. That is three times what a pair of head lamp bulbs draw. Leaving the lights on used to ruin a good battery in less than two hours back in the 1970's and 1980's. Drawing 30 amps will ruin a good battery in under an hour, when you do not have a working alternator to run the electrical system. This is how I know your alternator is working. Now, ... It can have other problems that can reduce its maximum output to exactly one third of its rated maximum current, but the symptoms for that do not match anything you are observed so far.

You need to perform a test for a drain on the battery. That involves removing the battery's negative cable, and inserting an amp meter between that cable clamp and the battery's post, but things get a little tricky on mid 1990's and newer vehicles. Yours is likely to have a computer that needs up to twenty minutes to go to "sleep" mode. Until then, it can draw up to three amps which will blow an internal fuse in most meters. Also, if you do anything to break the circuit for even an instant, including simply switching scales on the meter, that will wake the computer up again, then it will draw that high current until it goes to sleep mode again. To avoid this heartache and frustration, you need to bypass the meter with a small jumper wire at the appropriate times.

Do you have a digital volt-ohm-amp meter and know how to use it? If you want to do this test, I will describe the procedure in a lot more detail. You will need that meter and a jumper wire, and the dome light switch will have to be rigged so the light will not turn on when the door is open. That is so you can pull fuses, one at a time, from the inside fuse box.

There is a number of things to look at for the new battery. First is the posts have to oriented correctly. Except for some new vehicles, Chryslers and GMs always used the same orientation. I remember it by saying, "I need a battery right away". When looking down on top of the battery, with the posts on the side "away" from you, the positive post is on the "right" side, hence, "right away".

Next, it has to be a 12-volt battery. You have to look pretty hard to find a 6-volt for older farm tractors, 8-volt, I think for golf carts, and 24-volt for semi trucks.

The third thing is how they mount in the vehicle. Used to be mostly with a metal rod over the top, but Ford used plastic bars that usually broke in a few years. Both used bolts or rods that hooked into something down low. Today a lot of vehicles use a metal plate or a plastic block that hooks over a lip on both sides on the bottom of the battery's case. The battery needs to be bolted down to reduce vibration, which will greatly shorten its life span, and so it can't slide over and get chopped up in the radiator fan. That wasn't a pretty sight when it happened to me on the race track!

All of these things determine which vehicles a certain battery will be listed as fitting.

The biggest confusion comes from the electrical ratings. The main one is "cold cranking amps", (CCA). Use that number to compare one battery to another one. This is one area where car manufacturers seem to not skimp. Your Jeep probably came with around a 650 CCA battery. That means it can supply up to 650 amps while maintaining a minimum of 9.6 volts, for at least 15 seconds, at a specific temperature. That is either 0 degrees or 32 degrees. I can never remember.

It only takes up to 300 amps to get a starter motor turning, and once it's up to speed, it only draws 100 - 150 amps. A 650 CCA battery is more than sufficient for the job. Normal thinking is "bigger is better", but that doesn't necessarily apply to replacement batteries. Just because the new battery has a higher CCA rating, it isn't going to crank the engine any faster, and if you have a failure to start, it isn't necessarily going to crank it any longer. It is simply capable of delivering higher current if it has to. For most of us, buying a battery with a really high CCA rating means we're buying more than we need or will ever use, so we're wasting our money.

There's a trade-off to that higher current rating. As all batteries age, the lead flakes off the plates and collects in the bottom of the case. Once that lead builds up high enough to touch the plates, it shorts that cell, then the battery must be replaced. To get that higher CCA rating, the plates have to be larger. That leaves less room at the bottom of the case for the lead to build up. That battery will develop a shorted cell quicker than one with a lower CCA rating and more room in the case. To address that trade-off, the case can be made physically larger to make room for larger plates. We call that the "group number". One of the two most common group sizes is "group 24". Those fit in the spaces provided in the majority of cars. Trucks and many cars can fit the larger "group 27" batteries too, and they will mount the same way.

Ford used to have a number of odd-size batteries, and now GM is doing that too. Chrysler has always been famous for real good parts interchangeability between years and models, but even they are going to a number of custom-size batteries. This is where those applications charts will help you find the right battery for your vehicle. Basically, if it fits and can be bolted down, and the cables match the posts, it should be okay. It costs the battery manufacturers very little to add a little lead and end up with a higher CCA rating. To say that a different way, there is very little incentive to make a replacement battery that's smaller electrically than what came in your vehicle originally. Given the age of your Jeep, the battery has been replaced a number of times already, and the previous owner likely installed one larger than the original, so just because you install a smaller CCA battery, it might still be bigger than the original battery was.

Here's a link to a related article:

https://www.2carpros.com/articles/how-to-replace-a-car-battery

My '80 Volare came with a 350 CCA battery, and that was an upgrade included in a package that included FM radio, and a bunch of plastic bolt-on "Road Runner" body panels and tape stripes. That battery was so small, unscrewing one cap almost caused all of them to unscrew because they were so close together. Drove that car its first two years back and forth to college in miserable Wisconsin winters. It never failed to start the engine, even after sitting for three weeks over Christmas break. It was 30 below the day I went back, and the engine started just fine. Replaced that battery when it was more than five years old only because I didn't trust it because of its age.

Your battery should be fine for the size engine you have. Replacing it with one with a higher CCA isn't going to solve a battery drain problem.

There is a clinker in yer thinker. I have a suspicion your battery was not listed for your vehicle because it is considered a truck, not a car. Truck batteries are expected to bounce around more which can be expected to shorten their life span. Therefore, they often come with shorter warranties; typically only three years instead of the more common five years. I cannot emphasize enough, the battery is not causing the problem. You can put one in big enough to start the space shuttle, but that still will not stop the drain. Think of a small leak in a municipal water tower. Your answer to stop that leak is to put the tower on longer legs. What you need to do is address the leak, not the size of the tower, or its height. What you need to do is address the drain, (electrical leak), not the size of the battery. Once the drain is solved, you can put in a battery that's half of what you have now, and it will work fine.

Your friend should have told you to disconnect the battery's negative cable, not the positive one. Disconnecting either cable will stop any drain, but we always say to do the negative one because if you bump a metal hold-down bracket or any part of the body sheet metal with the wrench while it is in contact with the cable clamp, nothing will happen. You just go about your business. If you bump the wrench into something metal while it is touching the positive clamp, Fourth of July fireworks will take a back seat to what you will produce. If you are lucky, there will just be a lot of sparks. If you are as unlucky as one student who did this many years ago at school, the wrench will weld itself in place, become red-hot, and melt and bend under its own weight. Rather than take a chance on that, just take the negative cable off first, and always reconnect it last. When you are replacing a battery, once the negative cable is off, if you bump metal with the wrench on the positive cable, nothing exciting will happen.

Be aware too that you are going to have a low-idle speed problem every time you disconnect the battery. For everything else, the Engine Computer will rebuild what it lost in memory as soon as you start driving, without you even noticing. But "minimum throttle" needs to have certain conditions met for that relearn to take place. Until then, the engine may not start unless you hold the accelerator pedal down 1/4". You will not get the nice "idle flare-up" to 1,500 rpm at start-up, and it will tend to stall at stop signs. To meet the conditions for that relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

If you suspect the CD player as the cause of the drain, pull its fuses out, then see what happens. There should be one for the radio, and a second one for the memory circuit for the clock and station presets. That is always tied into some other circuit that is always live. Chrysler almost always ties that into the interior lights fuse, so pull that one too.

A common place to find wiring problems, especially intermittent ones, is with the wires that run between the door hinges. Those often fray and break. Once the drain test shows the amount of current being drawn, we can often make generalizations as to the cause. For example, one under-hood light that sticks on will draw close to one amp. Same with one brake light bulb. A glove box light draws close to half an amp. That can take a couple of days to drain a battery. Other things I have run into are power seat switches on the seat itself that get hung up in the upholstery, wiper motors with defective "park" switches that don't quite turn off, aftermarket radios that are connected to unswitched power circuits, and remote amplifiers that fail to turn off.

I am not fond of those franchise shops for electrical work. Around by me, they hire the young kids with little experience and no formal training. A much better alternative would be to find a nearby community college with an Automotive program, and see if they can help. We were always looking for live work to give our kids real-world experience. The cost will be real low, but the trade-off is it can take weeks to get the vehicle back, and they will only work on it while they are studying Automotive Electrical. To work on an electrical problem in, ... Lets say, Brakes class, would take work away from the local shops that hire the graduates. They may only do electrical work once or twice per year, especially at the smaller schools. The instructor can tell you if they need work and when they can do it.

In the instrument cluster, you'll find a bunch of 194, ... What I call "peanut" bulbs, because they're about the size of peanuts, (as opposed to the larger "acorn" bulbs), but that is a story for another day! Those 194 bulbs where fairly universal among all car brands and models for many years, so you can find a pile of them in any pick-your-own-parts salvage yard. These bulbs have an unusual characteristic where they turn black inside over time. Even though they might not be burned out, they give off very little light. You will find these for a lot of license plate lights too. As a side note, I have to visit a yard soon to get about 160 of the twist-in sockets these bulbs plug into. Need them for a new display board I'm building to sell LED versions of these at an old car show swap meet. 1980's and 1990's Jeeps are some of the easiest instrument clusters to remove in a salvage yard. Often just need a Philips screwdriver and nothing more.

The group 24 and 27 batteries are the only two I have memorized because they used to be so common. I suspect the biggest difference with a group 34 is it probably has the two tabs on the bottom for the hold-down bracket, but the height could be shorter too for vehicles with lower hood lines, or something like that. Regardless, if it can be bolted down, you are good to go.

With no nearby community college, my next suggestion is every city has at least one shop that is real good with electrical problems. I am quite proud to say that in over nine years of teaching Automotive Electrical, I had one student who just could not comprehend basic electrical theory. That is common in our field because we're used to seeing things and manipulating them. Cannot see electrical current, so it is hard for us. Anyway, we sat in the classroom one Friday night until 11:00 p.M. That is when he finally got it. Today he is working for the premier electrical shop in my city. You might ask some other mechanics who they recommend for electrical work. That shop might solve the problem faster than at any other shop, which will save some bucks.

Just thinking out loud, ... When you turn the key in the door lock, there is a switch that sends a disarm signal to the Body Computer to turn off the anti-theft system. You only hold the key in that position for a fraction of a second, then return it to centered so it can be removed. What if the wire for that switch is broken between the door hinges and is touching a frayed adjacent wire? That is one way an inoperative door lock could be related to a drain. Those touching wires could be sending the disarm signal continuously. That is the kinds of things we have to consider when looking for a drain. Once it is solved, we usually find something that works properly now that should have been a useful clue.

Made a road trip to Walmart to see what the differences are. A group 34 battery is 1/2" shorter than a group 24, and the caps are recessed. That means your 24 is one inch taller. Width and length are the same. I have the same issue with my 2014 Ram. It calls for a weird battery with recessed posts for hood clearance, but after letting it sit all winter and freeze, I drove it to the battery store with a borrowed full-size group 27 and had no clearance issues. Under just the right set of conditions, the engineers found a special battery was needed, and rather that try to confuse us with a pile of choices, they just picked the battery size that would work in every application. Someone might require that special battery, but my truck does not.

The 1993 through 1998 Grand Cherokees are all listed as needing the group 34, but if you did not create a bulge in the hood or sparks when you slammed it shut, you can get by with the group 24. That might not be the case in a different year, or perhaps with an optional hood style.

It was interesting to note that 1999 and newer Jeeps call for a group 65. That battery is the same height as a group 34, but it is one inch longer. That does not mean you must put that one in. A group 34 would fit and bolt down just fine, with an inch of room left over. By the way, all three of these have the mounting tabs on the bottom. The book lists the cheaper group 24 as having 650 CCA, and the original for your vehicle is listed as a 600 CCA. As long as the posts do not hit the hood, as I have said multiple times, the battery you have will be fine. If you buy the other one with 800 CCA, you will be buying more battery than you need or will use.