Can I diagnose which Ignition Coil went out?

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Oct 28, 2019
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Southern California
I have a 2000 Land Cruiser. I’m the
Original Owner. I have 265,000 miles on it and have had a few coils go out already.

I feel like I’m getting ripped off this time around with estimates I’m getting.
I found out the hard way before that I have to use Denso coils. All others have failed.
I can get help with getting the coil installed but my dilemma is how can I find out which coil is bad?
I know the symptoms and it’s definitely that...but please tell me there’s a way to know which one?
thanks!
 

jLB

Recovered from back surgery, and still grumpy!
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OBD2 code reader?


 
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Oct 23, 2014
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San Jose, CA
I’m guessing I can buy that....? I’ll google it..thanks!
Yes, you can buy. I bought a bluetooth OBDII reader on amazon (veepeak i think?) and also paid for an app. If you dont plan on doing a lot of wrenching on cars you can also just go down to the local autoparts store and most of them will scan your car for free (then sell you the needed part)
 

jLB

Recovered from back surgery, and still grumpy!
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I’m guessing I can buy that....? I’ll google it..thanks!
It's my understanding that many auto parts stores will read the code for you for free, although I prefer to have my own.

If you look at the thread that I linked above, it will show how to tie the "code" to a cylinder.

Depending on location, swapping a coil pack can be fairly trivial. I let my son do the last one on his vehicle. He's not terribly mechanically inclined, but he was grinning from ear to ear after fixing it himself.
 
Last edited:
Joined
Oct 28, 2019
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Thank you so much for the info! I’m going to try to go to Auto Zone in the morning and hopefully they can scan it for me.
My dad is going to help me put it on and this time I’m going to watch and learn. If your son can do it then I’m hoping I can learn too! I’m willing cause I like to save money! 😂
 
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Yes, you can buy. I bought a bluetooth OBDII reader on amazon (veepeak i think?) and also paid for an app. If you dont plan on doing a lot of wrenching on cars you can also just go down to the local autoparts store and most of them will scan your car for free (then sell you the needed part)
sorry guys! I’m trying to learn how to use the forum! I’m a little rusty! Thank you soooo much for all your help and advice! I’ll try to ask for a diagnosis at Auto Zone or O’Reilly’s and I’ll be more than happy to buy a few of the Coil packs cause ya know I’m gonna need them! No complaints though. That’s the only thing that’s gone wrong with my baby in 20 years! Can a girl ask for anything more?! 😀🚘🔧
 

e9999

You want to do what...?
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If you'd want to save a trip and possibly some money, in the old days you'd disconnect the wires one at a time and see which one did not result in a change in engine idling. Is there a way to do that easily on the 100 or is everything there brute force-proof? Sorry, forgot what those coils look like. And maybe the V8 is too smooth for that too. Or if you have a good spare one on hand, you can replace them one at a time, obviously, and see what happens but that's not very time effective.
But, anyway, yes, if you are going to keep this truck for a while, an inexpensive OBD2 reader is a good investment, the cheaper ones are (way) less money than having your typical dealer read a code once for you; and will save you a lot of time. Just make sure it can read the codes you may be interested in. Or buy a combo code reader and data reader and you'll be able to monitor the engine in real time.
I don't know that I'd buy a bunch of spare coils, though, you may never need them and they are not that cheap, but eh...
 

medtro

 
 
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Or if you have a good spare one on hand, you can replace them one at a time, obviously, and see what happens but that's not very time effective.
Swapping a good spare coil one at a time may not work well if you have more than one coils failed.
 

Hugh Heifer

Georgia bound.
 
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Rome, GA bound
The last one of mine that went did not throw the code to my Scanguage but did to my OBDII reader. Odd.

I bought my Denso coils from Amazon and always carry a couple spares.

Changing them is a 2 banana job just cuz if you are short, reaching across the engine bay can be uncomfortable and on the passenger side you may have to take some extra stuff out to get to them (or it).
 
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west michigan
my first coil failed on the way home from florida. I replaced with cheap autozone crap, it went bad again about six months later. I replaced with denso, but you already know to use denso. The next one failed while pulling the camper home. Luckily i had a back up. But after that i went ahead and replaced them all and ordered 1 spare. That was 2 years ago. I haven't had a check engine light since.
 
Joined
Oct 28, 2019
Messages
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Southern California
If you'd want to save a trip and possibly some money, in the old days you'd disconnect the wires one at a time and see which one did not result in a change in engine idling. Is there a way to do that easily on the 100 or is everything there brute force-proof? Sorry, forgot what those coils look like. And maybe the V8 is too smooth for that too. Or if you have a good spare one on hand, you can replace them one at a time, obviously, and see what happens but that's not very time effective.
But, anyway, yes, if you are going to keep this truck for a while, an inexpensive OBD2 reader is a good investment, the cheaper ones are (way) less money than having your typical dealer read a code once for you; and will save you a lot of time. Just make sure it can read the codes you may be interested in. Or buy a combo code reader and data reader and you'll be able to monitor the engine in real time.
I don't know that I'd buy a bunch of spare coils, though, you may never need them and they are not that cheap, but eh...
That’s EXACTLY what my dad thought of doing. Intelligent minds think alike! Thank you! 😀
 
Joined
Oct 28, 2019
Messages
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Location
Southern California
The last one of mine that went did not throw the code to my Scanguage but did to my OBDII reader. Odd.

I bought my Denso coils from Amazon and always carry a couple spares.

Changing them is a 2 banana job just cuz if you are short, reaching across the engine bay can be uncomfortable and on the passenger side you may have to take some extra stuff out to get to them (or it).
The best prices I found online were RockAuto and Amazon. About $55 for a Denso Coil. Unfortunately I don’t have time to wait for the shipping. So I have to suck it up and buy it from Napa for $84 🤦🏼‍♀️ Auto Zone was $125 🤔 and O’Reilly’s was $100.
I’m going to see if they can scan my truck. I’ll keep you guys posted. Now I just have to see if they can show me where the failed one is located. Cause when they tell me (example: coil 2 fail) I have no idea where that is...I guess I look for a diagram! If anyone has one can you please post here? Thanks much! Everyone is so helpful here! 😀💖
 
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Update:
I went to Napa and they actually gave me a good discount just for adding a third item (air freshener trees). Got the coils for $65.00 each. They told me they don’t scan cars and he said he was not sure if the other places did it anymore.
I got super lucky that a mechanic walked in that they have been recommending for over 30 yrs. He offered to scan my truck for me for free out of the kindness of his ❤....It was Cylinder 2. And for good measure he offered to put it on for me. So I saved my dad a trip and all turned out well and I found a new honest mechanic which to me, was the best bonus! Thanks again everyone for your help!
 
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The coils and plugs are SUPER easy to do, but yeah. Def use DENSO coils and the Denso Power Iridiums if you can, I like them quite a bit. just last week, the ONE final coil and/or plug was bad and failed but I carry my ODBII Reader and diagnosed in 5 seconds replaced completely 20 mins later. It's literally the easiest thing on the truck to do, but DEFINITELY replace coil AND plug at the same time if you can and always carry a spare with you and tools to do the job. The Densos SHOULD last a LONG time like the OEMs (200k+).
 

2001LC

 
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Colorado
Coil going out, may be a sign your spark plugs are getting "long in the tooth" or walking out. Plug gaps of 1.1mm is spec, 1.2mm and they're useful life is done, 1.3mm any they're starting to cook the coils..

 
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