99 Jeep WJ 4.0L ignition coil issue

[@GabrielGutierrez-xt1vk]

The 99 was the only WJ with the connector for the wiring on the coil pack facing down. For the rest of the WJ run (00-04), the connector is facing upward.

[@johngaston308]

I know this is a 9 year old video but its the only thing I've found that shows this modification. Pretty awesome.

[@jamminmechanics]

@@johngaston308 Hopefully help some fellow Jeepers. I run into this problem still. Simple reconfiguration and it's good to go with new coil rails 👍🏻

[@ryanraymond3037]

I want to extend many thanks to you, I have a 99 Grand Cherokee and the coil conditions have been declining more and more. I did look into another coil and seen that the little adapter was in fact $65 in my area and had to be special ordered and there was only one vendor. I obtained a coil from a friend that was junking his jeep due to a frame issue and I was able to take the coil. I originally swapped the coils and quickly found out that my jeep was not very happy. After calling my friend that I received the part from, I found out the coil was only a month old. You video helped so much and saved me a good chunk of cash. Less than one hour it took and now all my power has been restored and she wants to go!! Thank you so very much!! Ryan J. Raymond Putnam Connecticut

[@EisBlade]

Since you swapped the end wires and swapped the middle two wires, you basically just flipped with wire harness over and reinserted the wires into the plug. Same result. Great video that saves people a lot of money. Thank you. (If I'm wrong about the wires I'll pull my comment so as not to confuse anyone, but that's how the wires line up after you did all the swapping.)

[@jamminmechanics]

Yes, it's is flipping the wires in the plug. That's all that the expensive adaptor does, it plugs into the original harness and flips the circuitry. You can easy flip it in the original plug, as demonstrated in this video

[@jamminmechanics]

Example: Flip the original *-+= over to =+-*

[@MrNiklas1996]

What if the flip is not working? Firing up great and just shutting off right after?

[@racyfreeman317]

So wouldn't just flipping the connector over be the same thing?

[@Freeman-dp9vv]

What is the order of colors from the left, because I could not see it better?

[@Freeman-dp9vv]

Note I have a 2000 Jeep Cherokee

[@jeremyc3802]

you saved my butt! for over a year i have been trying to diagnose the misfire i had. checked the plugs, injectors, rocker valves.. problem was I'd get a new coil pack and it'd run worse. no mention of the wires anywhere online or stores. THANK YOU FOR MAKING THIS VIDEO!

[@jamminmechanics]

You're welcome. I'm trying to get a bunch of videos like this up this year! Stay tuned. Check out my FB page for Jeep WJ's! facebook.com/groups/jeepwjclub/

[@alancardin7927]

I was very apprehensive about performing this mod on my 1999 Grand Cherokee, but thanks to your video, I was successful. It was not as bad as I feared, and the results were unbelievable. I did not realize just how bad my coils had gotten. The 4.0 hasn't run this smooth in many years. Thank you!

[@garry8510]

Just rewired the plug on a 99 Grand Cherokee using the steps in your video, problem solved vehicle is working again after been down for several weeks, the guy had several mechanics look at it and all of them came up with all sort of crazy reasons why the jeep won't run. thanks to you this poor guy is out of this misery.

[@williampadilla2381]

Can this be the reason y my new coil pack dosent spark

[@n54ne15]

man same thing did yours work after switching wires

[@emanuelescobedo7246]

I'm having this very same problem now. Hope this will get my wife's truck running again thank you for this great instructional video...It's been a week now time to try this lol let's pray to God it works.

[@gabyrivero7408]

Emanuel Escobedo did that work for you?

[@toddlockhart605]

What wires go where

[@Ace-ou9vv]

question. Does this fix apply on the 2000 wj? And what does it do without the fix? Jst cranks?

[@junker246]

I'm working on my sons 2001 cherokee 4.0 what year or how can you tell this is the problem? im getting po 351 po352 an po353 codes is this possibly the fix? it is a new coil just installed.

[@jamminmechanics]

Check the direction of the plug from the old rail vs the new one. One points up, the other points down. That's how you'll know that the polarity is reversed

[@--gmoney5572]

Did you ever solve that issue? I have the same problem with my jeep. It has had every part in the series replace! Any help would be appreciated thanks!

[@beboboymann3823]

What? What on earth is this all about? Am I hearing that if I go to NAPA and buy a replacement coil for my TJ 4.0 that the new coil will be wired wrong? Why is that?

[@cuatez66]

I have a 04 Laredo whit the p0353 replaced coil pack does your video cover 04 as well or do in have to look some where else

[@jamminmechanics]

'04 should have the new wiring design and shouldn't need the adapter or rewiring

[@PaulSmithDYL]

Thank you!! I knew 2 new coils couldn't be bad!

[@moorenick3690]

Was your truck not starting at all and then u did this and it started

[@twright3802]

This worked great! My plug fell apart when I tried to disconnect it from the coil so I had to figure out the color scheme for the wires. After I did that I was able to put the new plug and coil back on in one try and my 2000 Grand Cherokee fired right up. Thank you so much.

[@johndayberry6366]

I have a 1999 Jeep WJ with the 4.0L engine. Have been troubleshooting for days. Engine runs very bad, very weak spark on 2,3,4, and 5. No spark on 1 and 6. Haven't owned it very long. My thoughts are someone replaced the Coil Pack and didn't change the wiring. The hot wire on the plug is on Pin 3. Haynes manual shows it to be on Pin 2. Would that verify the plugs needs to be rewired like your video shows? Thanks.

[@johndayberry6366]

Changing the ECU fixed the no spark problem !!

[@brendaroldan4642]

I pulled the bottom of the connection off and the white part didnt come out 😶😞 how do i get the wires out?? Help lol

[@darrellwilliams4520]

I have an '01 GC and I just got new coils. I had trouble getting to and removing that clip. Can you provide some advice, and is switching the wires absolutely necessary?

[@BigSkyDronePilot]

so glad to see this info about the wire harness repair for jeep coil pack. would cost $80.00 for adapter!!!! Thank you so much!!!

[@jamminmechanics]

Thanks for watching!

[@dunlopstar]

This helped me to see the wires bare and out of the connector. I just had to replace the ignition coil, and cause of the stupid ass reverse tab design, I had to break it to release the old coil. Now I'm splicing in new cable to connect directly to the pins on the new coil until I can get a replacement connector to splice in from the states. I didn't photo the cables before they ripped out the connector so had to guess, two ways so far, one floods the engine, the other drives up to second gear. I've had the green cable on the outer side though so I'll try another combo based on this! Props

[@MrsBuddevil]

What were your end results?

[@dunlopstar]

@@MrsBuddevil I just had to keep guessing. I found that the wire colours were different for certain GC’s, possibly because of EU and US markets. Half the permutations misfired and didn’t even turn the engine over, so the other half I just had to keep trying. One let it drive but limited the power at 40mph, the last permutation I tried was correct. I had to splice in new cable in order to get the length I needed to reinstall the coil pack properly. I covered them in heatshrink tubing to cover the splice points. The best way to do this is using a multimeter but I chose the hardest route. Any new cable you add in has to be right gauge in order to hold the right current. I forget what amperage it had to be but it’s something to check.

[@lostpharaoh8909]

What is the name of the adapter piece and where can I find it?

[@Garthx1]

I know this is a old comment but the adapter is called ignition coil connector and if you go on rock auto they have it for $12 bucks while the parts sell it for $80 bucks

[@TILTED_DAN]

How do I take the cover off ?? :( break it does it matter ???

[@jamminmechanics]

There's little click tabs that hold it together. Keep in mind that this only works for WJ's that have the old coil design and you need to switch to the new design

[@danlong9772]

Thank you , changed coil pack in my 01 wrangler wondered why misfire , now I will check wiring of plug .

[@tonyhillis8869]

Working just as you said Thanks 🚘🚙🚗

[@tiger.6509]

The coil rail I did exactly like you said it started it ran good took it for a drive , I came back turned it off and now won’t start ??

[@adriansingleton2856]

Curious to see what did you do to get it started again

[@jamminmechanics]

Strange... Could be a different issue... Did you figure it out?

[@tiger.6509]

Small little blue ,plug, I put in there on the black plug I didn’t put it in far enough , I reworked it ,I did that plugged it back in it started right up running like a champ

[@jessicamcdaniel7396]

Thanks for the knowledge cause they sure don't tell ya u need a plug connector till after u buy the coil rail

[@martincherezzabornoguzader1321]

Огромное тебе спасибо 👍👍👍 Я догадывался об этом но не решался сделать. Боялся повредить мозги. Посмотрел твоё видео, сделал и джип заработал как положено 👍

[@robertrojas3223]

excellent information, thanks friend

[@jamminmechanics]

Your welcome

[@kedamono8833]

hey my jeep has same problem if I try ur theory will it mess up anything and do u have a follow_up video

[@jamminmechanics]

I can do a follow up video if you'd like. If you wire it as shown, it works 100%. I still have the Jeep, and it's my daily drive! :)

[@brendaroldan4642]

Oh my god it worked so far so good .! Hope it stays like that

[@darrellwilliams4520]

Also, how difficult is it to take apart the plug? Looks complicated.

[@jamminmechanics]

Darrell Williams, the plug change is needed for most replacement coil packs on the 4.0l Jeep WJ's

[@darrellwilliams4520]

Jammin Mechanics if the plug is not changed, what difference should I be looking for? What is most noticeable?

[@jamminmechanics]

It's not difficult to do at all if you have experience with electronics. If you're a beginner, it might prove somewhat difficult. Having the correct tools is essential

[@jamminmechanics]

So, with the coil pack, the difference between them is the plug on the old one faces out and up, while the new one faces down. The difference in the wiring is that the terminals are reversed between the two. Replacing an old style coil with a new, without changing the plug, will make it so that your Jeep won't run, or will run vary poorly. For me, mine wouldn't run at all until the change was made

[@darrellwilliams4520]

Jammin Mechanics well I changed the coils the other day and it runs. The power is there, but sometimes I get a little stutter in the gas, I can feel it slightly in the pedal. Other than that, she runs fine.

[@danIstrate1994]

Hey ! I have a 2002 GC, 4.0 I-6 just like yours. For some time, after it has been standing for a year, I keep having problems starting it up. When it was hot outside, it would usually start the 2nd time. Now that it's gotten cold, I started it after 6 or 7 tries. Do you think the coil might be the problem ?

[@jamminmechanics]

That's a tough case. I've had a similar problem with this Jeep... hard starting and such... Ended up being a IAC valve. Also, I had a faulty signal wire to the TPS. Replaced them, and it's been running great ever since!

[@chrischafin3237]

I had the same problem and did the same thing no way I spent $50 or an adapter

[@rogeliobarrera3642]

Como. Desactivo la. Alarma del Jeep gran cherokee

[@boshhutchings8145]

⭐⭐⭐⭐⭐

[@mikewiedrich3751]

I12

[@seanballard2062]

Absolutely the dumbest things I've seen in awhile. Fix it back to oem.

[@jamminmechanics]

The old coils are no longer available, only the new ones with the different wiring. Only other fix is to purchase the $60+ "adapter harness"