Jeep Wrangler TJ won't start? Read this!

Glad you got it sorted out without much of a hitch!
If you want an Optima battery for your Jeep, then great. Optima batteries in normal street vehicles are NOT a better choice than a regular battery. Optima batteries are superior for vehicles that take a beating, i.e. race cars, rock crawlers, boats, mud bogging, etc. There is also no longevity advantage by purchasing an Optima over a regular battery. I've seen numerous Optima batteries go out within 5 years, as have just as many regular batteries.

If your battery has been working just fine and suddenly you need to jump start your Jeep, or any other vehicle, have the battery tested. Of course this means charging it first. Make sure you test the newly charged battery 2 times. The battery could hold only what is commonly referred to as a "shallow charge." After charging the first test will look great. The second charge will have a very significant drop in amps. Meaning a 100+ drops in amperage. If this happens, your only recourse is to replace the battery.

Finally, today's batteries are maintenance free. This means if the battery is dead and/or the acid level is low. You can pop the caps off the battery to check. If the acid level is low, putting water, or even new acid in your battery won't help you. Doing this is kind of an urban legend. You may be able to do this to help extend your batter's life, but pretty much only to get you to a parts house so you can purchase a new battery. But, even that isn't guaranteed. Again, the myth of putting water in your battery will not extend your battery life. You only take the chance of spilling acid onto yourself or onto your vehicle. This could cause you acid burning and the acid will eat through any paint it comes into contact with which will expose bare metal and allow rust to begin eating away on your Jeep and NO ONE wants that.
 
Could this have something to do with the temperature?
the only thing that I can think of that would fit in that is the battery. However, I’ve never had to charge the battery or mess with it at all to get it to start.
I ask because I was thinking, it almost always starts when I’m ready to take a look at it. When is that? When it’s a little nicer out. Possibly a coincidence.
Definitely not the battery. Load tested fine this AM. Jumped power to the solenoid and cranked fine and started. I let it run for about a minute and shut it off. Jumped the solenoid again, cranked, but wouldn’t start.
I don’t get it.
Jeep for sale.
 
Ok, it's my turn. Bought an 02 Saraha a few months ago and decided to put new halo LED headlights in for Christmas. Had battery unhooked for about a week. Put in the new headlights, ran the halo DRL to the cigar lighter fuse behind the glove box. Hooked the battery up. Headlights work, DRL works. Go to start the engine and everything goes out. Now I just get an annoying chiming like to door is open. Nothing lights up, nothing at all. Just the door chime even with the door closed. Any thoughts? I am guessing a fuse blew. Thanks for your help.
 
Ok, it's my turn. Bought an 02 Saraha a few months ago and decided to put new halo LED headlights in for Christmas. Had battery unhooked for about a week. Put in the new headlights, ran the halo DRL to the cigar lighter fuse behind the glove box. Hooked the battery up. Headlights work, DRL works. Go to start the engine and everything goes out. Now I just get an annoying chiming like to door is open. Nothing lights up, nothing at all. Just the door chime even with the door closed. Any thoughts? I am guessing a fuse blew. Thanks for your help.
Likely your battery. Charge it or jump-start and see if you can get it running. Have battery load tested. Might have just lost it's charge when you were working.
 
That was spot on! Hooked up the battery charger and it read 88%. Let it run all day on 5A. Hooked everything back up and it works like a champ. Thanks for the help.
 
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Intermittent problems are the worst. If you haven’t run across the very specific issue before, and the problem isn’t actually occurring at the time you go looking, it’s really just an educated guess at best. Couple that with a starting issue that seems to tick up when the weather is crappy (by New England standards).
This has been such a pain in the butt.
Normally, this is an extra vehicle, so no big deal. Not the case lately; it’s my only wheels. Unfortunately over the holidays...fortunately the weather this week has been amazing! So I got tome to run through some good logical testing, instead of what test I could pull off while my fingers still worked.

So, now for the info...
This possibly should have been one of the very first tests, so kind of embarrassing.
I took my Power Probe and sent power to the #30 Starter Relay port when it wasn’t starting with the key in Run position and it did not crank. That should isolate the circuit between relay and solenoid.
As true to this problem, it started a few minutes later.
With the above test in mind, I came up with a simple Relay Rescue Kit.

5526D4D0-2352-4384-8D9F-01C66A65018C.jpeg


78C6E835-B006-4466-ADB2-BE974DC2C93F.jpeg


The next time it doesn’t start, I can quickly plug this in and bypass that circuit. If it starts (which I expect it will), I’ll be confident I know where the problem is.
Normally, I’d just rip into the harness, but right now I can’t risk a can of worms that makes the Jeep inoperable where it’s mostly operable now.
 
Maybe the last update on this one.
Sure as it started getting crappy out, the Jeep would not start and I was heading to a family dinner. Opened my glovebox, pulled out the kit and installed it in about 3 minutes. Was on time for dinner.

I have it routed well enough where I'm going to leave it like that for now, till I get plenty of nice weather top pull it apart and repair it properly.

Thanks for the thread; it was helpful.
~Matty
 
If you want an Optima battery for your Jeep, then great. Optima batteries in normal street vehicles are NOT a better choice than a regular battery. Optima batteries are superior for vehicles that take a beating, i.e. race cars, rock crawlers, boats, mud bogging, etc. There is also no longevity advantage by purchasing an Optima over a regular battery. I've seen numerous Optima batteries go out within 5 years, as have just as many regular batteries.

If your battery has been working just fine and suddenly you need to jump start your Jeep, or any other vehicle, have the battery tested. Of course this means charging it first. Make sure you test the newly charged battery 2 times. The battery could hold only what is commonly referred to as a "shallow charge." After charging the first test will look great. The second charge will have a very significant drop in amps. Meaning a 100+ drops in amperage. If this happens, your only recourse is to replace the battery.

Finally, today's batteries are maintenance free. This means if the battery is dead and/or the acid level is low. You can pop the caps off the battery to check. If the acid level is low, putting water, or even new acid in your battery won't help you. Doing this is kind of an urban legend. You may be able to do this to help extend your batter's life, but pretty much only to get you to a parts house so you can purchase a new battery. But, even that isn't guaranteed. Again, the myth of putting water in your battery will not extend your battery life. You only take the chance of spilling acid onto yourself or onto your vehicle. This could cause you acid burning and the acid will eat through any paint it comes into contact with which will expose bare metal and allow rust to begin eating away on your Jeep and NO ONE wants that.

This statement is not accurate. While many automobile batteries today are "Maintenance Free" There are still batteries that are serviceable. A maintenance free battery is actually a misnomer. They call them that because they have sealed the caps to the battery body so the end user can not maintain the water level in each cell as it evaporates from heat. Granted they have designed the caps to condense as much vapor as possible so it so it does typically retain water longer than a maintenance type battery.
Maintenance type and maintenance free batteries are constructed the same internally lead plates submerged in liquid sulfuric acid. Optima, LifeLine, and other AGM or sealed lead acid type batteries use an electrolyte instead of liquid acid to prevent evaporation.
Maintenance type batteries are actually superior to maintenance free because people can monitor and keep water levels above the lead plates unless of course one does not like performing regular P.M. Adding new sulfuric acid is actually NOT the correct procedure for topping off an already charged battery, You should only use distilled water and then put a slow charge on the battery until it is fully charged.
 
I have seen many posts on this board with people incorrectly diagnosing starting issues, or giving advice that requires a lot more wrench turning and guess work than necessary. I figured I could make a little diagnostic write up to better inform people about how to test the system, and how it works in our Jeeps.

One thing to keep in mind is that the starters ONLY job is to turn the engine over. If your starter is cranking over the engine but it's not firing, your problem lies elsewhere.

The first step in properly diagnosing the starting issue you are having is to verify your voltage. If you are not getting enough power to the starter, you cannot properly start your jeep. Grab a voltmeter (NOT a test light, those are useless here), and a twelve pack. I prefer Guinness or New Castle, as they have a high Jive-osity ratio when working on my jeep, but anything will suffice. You may need a friend to give you a hand turning the key while you take some voltage readings.

1. First, we start with the battery. This is where you get your power from. If you have a load tester, hook it up to the battery posts (there is no need to remove any cables). Make sure your battery has a decent charge. 12V - 12.6V is acceptable here.

2. With your voltmeter on the batter posts, turn the key to the start position, and read what the voltage drops down to at the battery posts. If it drops below 10.5V or so, you either have a bad connection at the posts, low battery, or a bad battery. Make sure the posts are free of corrosion, charge it up, throw a new one in, do whatever. If you have the battery tested at a shop, keep in mind that you cannot correctly test a batterywithout it being fully charged. Once you have your freshly charged/new battery, throw that sucker in and if you still don't start, proceed to the next step.

3. Have you cracked one open yet? If not, do so.

4. Once you have verified that your batteryis able to produce enough current, you need to check your feeds to the starter. We will start with the ground, since that is more common of a failure from what I have seen. With your volt meter, put the positive lead on the positive battery post, and the negative lead on a clean metal surface on the starter body, or the solenoid mounted on it. Any clean metal surface on the starter will suffice. Verify that the voltage reading you get at rest is the same as the battery reading at rest. Have your friend (you gave him a beer too, I hope) turn the key, and note the the lowest point the voltage drops to. Remember the reading we got when trying to crank at the battery? You do not want to see more than a 0.5 volt decrease at the starter when cranking. If you drop more than that, you have resistance in your ground circuit. Trace it back until you find the point where the voltage is being lost. That includes the cable, the connection at the batteryend and the end that mounts to the motor, the connection where the starter mounts, everything in between. If you are having trouble tracing it back, just start at the starter and move the volt meter back one connection at a time until you get a good voltage reading. That will tell you exactly where you are losing your ground. Once everything checks good, we need to check the live feed to the starter.

5. Put the negative lead on the negative post of the battery, and the positive lead on the large post of the solenoid on the starter, where the live batter cable runs to. Perform the same tests as we did on the ground cable to check the live feed. Everything good? Let's check the ignition feed now.

6. Keeping the negative lead where it is, put the positive lead on the small wire connected to the starter. This is the ignition terminal, when you turn the key to the start position it sends power to this terminal to engage the starter. Take the same readings as we did on the cables. Note that this wire should ONLY be live with the key in the start position. If you have low/no voltage here, then you are not getting power through the ignition, and should check for a bad/broken wire, ignition switch, etc. In a Manual jeep, check to make sure the Neutral Safety Switch and related wiring is in working order.

7. If you have sufficient voltage present at the starter and still not cranking properly, then your issue is most likely the starter (or a seized engine). More than likely you can replace the starter and be on your merry way.


COMMON STARTING ISSUES:

RAPID CLICKING: 99% of the time it is low voltage to the starter. Check battery and feeds as detailed above. Basically you have enough current to engage the first coil in the starter solenoid, which pulls the plunger in and engages the drive into your flywheel, but not enough to power the holding coil which keeps it in while cranking. This causes the solenoidto release, and the re-activate since the current in the system is brought back up. this will happen rapidly, hence the click-click-click-clicking. VERY rarely it is an imbalanced solenoid on the starter. The voltage readings above will diagnose it properly.

NO CLICKING AT THE STARTER: Check for a loss of ground to the starter, or a loss of voltage at the battery. Check the ignition terminal on the solenoid for power when trying to start. If none of those circuits have any issues, the starter is bad.

JUST A CLICK: Again, verify the voltages. The solenoid could have enough power to engage and feed current to the starter, but a loss of current in the ground/cable/battery could be causing the starter to not crank properly. If the voltages are fine, change the starter.

STARTER SPINS, BUT DOESN'T CRANK THE ENGINE: The drive in your starter is blown or the gear is chewed. Change the starter (or drive if you are so inclined). Also check the teeth on the flywheel, make sure they aren't torn up. It is also possible (but unlikely under normal circumstances) that your drive shaft is snapped, or the planetary track in the starter is worn, in which case a new starter is in order.

STATER STAYS ENGAGED AFTER ENGINE STARTS: If the starter stops spinning when the key is off and the engine stops turning, check the ignition feed to the starter, make sure the ignition switch isn't faulty and supplying voltage to the starter when not in the start position. The drive could also be binding mechanically. If the engine stops turning and your starter is still spinning even with the key off, you have a low voltage issue. Basically what is happening is you have enough voltage to crank, but it is low enough that the contact diskin the solenoid is welding itself to the contacts due to heat from loss of amperage. Find your voltage drop in the battery/cables. I also suggest changing the starter/starter solenoid, as this causes the contacts to become distorted and chewed, and will cause problems in the starter.

CRANKS SLOW: Again, check voltages, change starter if necessary. Notice a pattern?

A NOTE ABOUT HAVING AUTOZONE TEST YOUR STARTER.

Autozone, C.A.P. and the likes cannot PROPERLY test your starter. I say this because every store I have seen test them just puts power to it to see if it spins and to check that the drive pops out. There are many problems that cannot be determined through that alone. Worn or gummed up brushes, a slipping drive, and worn contacts in the solenoid are just a few of the issues that can make a starter turn over on the bench, but not in your jeep. If have yours tested and they tell you it is fine, take it with a grain of salt.

Feel free to keep this thread alive by adding your input, suggestions and any more information I may have missed.
Hey chris just want to thank you for everything you do on this forum i know i speak for everyone when i say you have helped me more times then i can count on both of my hands keep it up bud!
 
Hey chris just want to thank you for everything you do on this forum i know i speak for everyone when i say you have helped me more times then i can count on both of my hands keep it up bud!

No problem, I'm always happy to help in any way I can :) More importantly, I'm just trying to put together a site where we can have all these TJ resources all in one place!
 
Intermittent problems are the worst. If you haven’t run across the very specific issue before, and the problem isn’t actually occurring at the time you go looking, it’s really just an educated guess at best. Couple that with a starting issue that seems to tick up when the weather is crappy (by New England standards).
This has been such a pain in the butt.
Normally, this is an extra vehicle, so no big deal. Not the case lately; it’s my only wheels. Unfortunately over the holidays...fortunately the weather this week has been amazing! So I got tome to run through some good logical testing, instead of what test I could pull off while my fingers still worked.

So, now for the info...
This possibly should have been one of the very first tests, so kind of embarrassing.
I took my Power Probe and sent power to the #30 Starter Relay port when it wasn’t starting with the key in Run position and it did not crank. That should isolate the circuit between relay and solenoid.
As true to this problem, it started a few minutes later.
With the above test in mind, I came up with a simple Relay Rescue Kit.

Screenshot_2020-01-07 Jeep Wrangler TJ won't start Read this (2).png


Screenshot_2020-01-07 Jeep Wrangler TJ won't start Read this (3).png


The next time it doesn’t start, I can quickly plug this in and bypass that circuit. If it starts (which I expect it will), I’ll be confident I know where the problem is.
Normally, I’d just rip into the harness, but right now I can’t risk a can of worms that makes the Jeep inoperable where it’s mostly operable now.

Hey badmatty,
I think I'm having the exact same issue you are. I have a couple questions about your "Relay Rescue Kit". When your jeep doesn't start are you taking the relay pictured out of its spot in the fuse-box and then installing the wires (harness) as-shown and plugging the relay back into the same spot using the "Relay Rescue Kit" harness? I'm assuming the black plug (circled in red) is providing 12V power directly from the battery but what/where are you plugging it into?
Thanks!
 
Hi all, my TJ died while I was driving and I can’t seem to figure out the issue. Fuel pump is working, spark plugs are sparking, but the engine won’t crank. The starter tries to start it but won’t get ignition. Would a bad starter cause it to die while driving or would it be a different issue. It’s also worth mentioning that I had just put 2 12in speakers in the trunk but the battery still works and the starter still runs as well. Thanks in advance for the help
 
Hi all, my TJ died while I was driving and I can’t seem to figure out the issue. Fuel pump is working, spark plugs are sparking, but the engine won’t crank. The starter tries to start it but won’t get ignition. Would a bad starter cause it to die while driving or would it be a different issue. It’s also worth mentioning that I had just put 2 12in speakers in the trunk but the battery still works and the starter still runs as well. Thanks in advance for the help
I'd start by removing both battery cables and cleaning the cables / terminals with a wire brush. If that doesn't work take the battery to the local auto store to get it tested.

From what I've seen it's battery or ground related issue when TJs won't start.

Welcome to the forum by the way.
 
I'd start by removing both battery cables and cleaning the cables / terminals with a wire brush. If that doesn't work take the battery to the local auto store to get it tested.

From what I've seen it's battery or ground related issue when TJs won't start.

Welcome to the forum by the way.
Thanks for the welcome I’ll definitely try cleaning the cables when I get off work will update later tonight!
 
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Well a defective starter will not cause your engine to die while driving but when you say "the starter tries to start but won't get ignition " are you saying the starter will not turn the engine over? Usually when your car dies while driving and then the battery will not turn the engine over after it dies the issue "commonly" lies within the charging system( i.e. alternator)....but if the car cranks over after it died and will no start then that's a whole different spectrum. Then you may be talking about a failing sensor( i.e. CKP sensor etc.)
 
Well a defective starter will not cause your engine to die while driving but when you say "the starter tries to start but won't get ignition " are you saying the starter will not turn the engine over? Usually when your car dies while driving and then the battery will not turn the engine over after it dies the issue "commonly" lies within the charging system( i.e. alternator)....but if the car cranks over after it died and will no start then that's a whole different spectrum. Then you may be talking about a failing sensor( i.e. CKP sensor etc.)
It tries to crank but the engine will not turn over, when it died it kind of bogged down as if it wasn’t reviving fuel but we ruled that out as the fuel pump still works fine it may be the battery or alternator but I’m im not wrong it wouldn’t die mid drive if it was the alternator as the battery still had acceptable power during and after it died
 
It tries to crank but the engine will not turn over, when it died it kind of bogged down as if it wasn’t reviving fuel but we ruled that out as the fuel pump still works fine it may be the battery or alternator but I’m im not wrong it wouldn’t die mid drive if it was the alternator as the battery still had acceptable power during and after it died
For clarification purposes, you're saying the engine "tries to crank" but "will not turn over"
By turn over are you meaning it will not start? or are you saying it will not physically turn the crank shaft?
I ask this because "crank" and "turn over" are effectively the same exact thing. If the engine is "cranking" or "turning over" at normal speed but will not fire and run on its own that rules out the battery being part of your problem.
 
For clarification purposes, you're saying the engine "tries to crank" but "will not turn over"
By turn over are you meaning it will not start? or are you saying it will not physically turn the crank shaft?
I ask this because "crank" and "turn over" are effectively the same exact thing. If the engine is "cranking" or "turning over" at normal speed but will not fire and run on its own that rules out the battery being part of your problem.
Okay then yes I was a bit confused the starter is turning the crank but there is no ignition
 
I would start by checking to see if spark is being delivered to your plug wires. You said you verified you had good fuel pressure? Did the engine just suddenly die while you were driving it (tach was buried at zero) and you had pulled over to the side of the road or did it slowly feel like it was loosing power as the car started to slow down before it died?