Coil pack test - Is there an easy way?

I know LS coils are pretty durable, but I'm having a hard time finding a procedure for testing them, with in the car, or on the bench.

Does anyone have a tip or two?

Umm, I have never wondered that actually.

Maybe there's a resistance test out there I'm not aware of? Like on Haynes Manual?

Easy way? Swap wires and see if the misfire follows. Are you trying to address a code? What is the code or problem?

OR VietVet said:

Easy way? Swap wires and see if the misfire follows. Are you trying to address a code? What is the code or problem?

Click to expand...

No codes. I'm trying learn how to test them. I have a multimeter and oscilloscope, and like to know how things work.

I have eight spare coils from my engine swap, and figured it'd be nice to know if they were all good.

I checked and Haynes Manual does not show any testing procedures for the V8 coil packs, only for the V6 engines, which are obviously different.

There's a guy on the GMT400 forum that swore LS coil packs fail left and right, Monday tru Sunday (same guy also says the SBC is superior because it has ONE coil pack vs 8, LMAO!) Anyways, I've been driving these engines (high 200k+ mileage too) now for a few years and thousands of miles and I can now say he's full of $hit. I'm sure they do in fact fail (what doesn't?) but the failure rate seems very low, especially the OEM ones.

You can probably get a good one, and compare the resistance to your 8 on the bench.

Or, I'd say just swap one by one on a known good vehicle and drive it a few days, if you don't get a misfire, put a piece of tape and label it: GOOD.

strutaeng said:

I checked and Haynes Manual does not show any testing procedures for the V8 coil packs, only for the V6 engines, which are obviously different.

There's a guy on the GMT400 forum that swore LS coil packs fail left and right, Monday tru Sunday (same guy also says the SBC is superior because it has ONE coil pack vs 8, LMAO!) Anyways, I've been driving these engines (high 200k+ mileage too) now for a few years and thousands of miles and I can now say he's full of $hit. I'm sure they do in fact fail (what doesn't?) but the failure rate seems very low, especially the OEM ones.

You can probably get a good one, and compare the resistance to your 8 on the bench.

Or, I'd say just swap one by one on a known good vehicle and drive it a few days, if you don't get a misfire, put a piece of tape and label it: GOOD.

Click to expand...

Yeah, I was under the impression they either worked or died, no in-between.

I have not looked but what does you tube say?

some info.


while you might be able to fire the coil in open air, you can't really test if they will fire a plug properly under load that's why it's standard practice when getting missfie code to swap the coil with another cyl. to see if the miss follows the coil.


not saying old guy us right, but they do kinda fail more often than what old guys are used to. it could purely be the odds of it happening is higher with 8 than one. or we seem to have gone backwards in quality parts wise. old coils might just have been better. I had a 96 with 325k when I sold it.. still on the oem coil. I got my 2011 with 130isj on it and it's already had one changed out.

now that said, the ls coils are very much more complicated. lots of electronics to fail in them. old coils are mostly just a transformer. ls coils do put out more spark power too.

the only way I know of is either you get some misfire from it or you don't
if the ones installed now are for sure working fine, pull them out and swap in your other set, drive it and see what happens if you have no problems after 3-4 days either leave them in or swap the others back in, failure rate is pretty low for oem

(the old fashion way)**if you can hear/sense the misfire but it doesn't throw a code, start pulling wires one by one until you can't hear the difference any more
(new way) may be to connect a scanner like the tech2 and log the misfire counts, then swap coils and see if the misfire follows the coil.

pretty sure they are basically a step-up transformer generating a high voltage pulse that shoots thru the spark plug ceramic to the electrode igniting the fuel , so you would likely need a high voltage tester and know what the specs should be to really call it "good"

a ohm resistance test can be done but the coil could still be no good because there is no load, which could be where it fails
there are little cheap tools sort of like a household power socket tester that shows if the coil is firing or not but still doesn't tell you if it is 100% or not.

Watch this and look at the tool he uses to see if the coils are sparking through the wires. We use our Tech-2s too.