New to scopes. Looking for some help

[Ryze]

I purchased a Modis for the scan tool and wanting to learn how to use a scope for diagnostic purposes. I get the general idea with it but it is still hard for me to understand how to set one up to diagnose a car.

example

today had a 2008 pontiac grand prix. 3.8l with a miss fire under load and idle. code p0300, with the mis-fire counter on 2 and 5 always going up.
I checked spark at the plug wires with a spark checker. no spark on 2 or 5. I suggest a coil. Well that didn't fix it.. Needed an ICM

How does one go about pinpointing the ICM instead of the coil?

I know very vague question, but I just don't understand how one could say it needs an ICM over a coil without throwing parts at it.

I figured since it was affecting only 2&5 (which are the same coil) it was for sure the coil. but I was very wrong. I don't like making these mistakes

[dave-m]

Easiest way before ordering parts is to just switch the suspected bad coil pack with one of the other two. If the misfire follows the pack then replace it. If the misfire stays the same you can take the pack off and check the now exposed terminals for power and ground.

Have never bothered to try a scope on the ICM Coil terminals, but if you set up for 15V, hook the ground and channel 1 to the proper polarity terminals, you should see a pattern while cranking or running, if it remains flatlined then you have a bad ICM. I don't use the scope as much as I should, so I usually play around with the settings to get a decent looking waveform whenever I do use it. Will be using it more now as I just traded my Solus Pro for a Modis.

[Crusty]

Coils are paired to cylinders. 1/4, 2/5, 3/6.
When one plug isn't firing, it could be the OPPOSITE paired plug/wire. When BOTH paired plugs arn't firing, it could be either or both plugs, either or both wires, the coil, or the module.
Pop the coil off, hook up an old fashioned TEST LIGHT, preferably an older one which will create a load, start it up, if the test light flashes, the ICM is signalling the coil. If the test light doesn't flash the light, the module is pooched.
That's how the service manual says to check 'em, at least on the old ones.
It's worked for years anytime I had two paired plugs not firing. Too simple so it often gets overlooked. HTH

[Skip]

Try useing the CTM portion of your Modis. It has a lot of component test information such as connector pinouts, test locations, as well as pre written tests for voltage resistance and waveform signatures.

[meatwad]

Hey Ryze-
Check this link out. This guy does a bunch of scope testing using the Verus and it might help lead you in the right direction as far as general scope usage goes.

http://www.youtube.com/watch?v=9MuAiPfIOhw&feature=relmfu

[pdanner]

how to determine coil or module

I purchased a Modis for the scan tool and wanting to learn how to use a scope for diagnostic purposes. I get the general idea with it but it is still hard for me to understand how to set one up to diagnose a car.

example

today had a 2008 pontiac grand prix. 3.8l with a miss fire under load and idle. code p0300, with the mis-fire counter on 2 and 5 always going up.
I checked spark at the plug wires with a spark checker. no spark on 2 or 5. I suggest a coil. Well that didn't fix it.. Needed an ICM

How does one go about pinpointing the ICM instead of the coil?

I know very vague question, but I just don't understand how one could say it needs an ICM over a coil without throwing parts at it.

I figured since it was affecting only 2&5 (which are the same coil) it was for sure the coil. but I was very wrong. I don't like making these mistakes

Here are two different pics. One car has a bad module, the other car has an open primary winding. I must sincerely apologize to the board that this is not a pic from my Verus or Vantage Pro. It is an old pic. and I don't have this one yet on my newer scopes. The Verus/Vantage Pro can do this same thing without a problem at all
The key to understanding what you are looking at is base circuit current flow and an increased dwell time from a module that is pretty smart.

[crackerclicker]

yep, that's certainly an old capture. pico 5 has been out-dated for how long now?

[pdanner]

yep, that's certainly an old capture. pico 5 has been out-dated for how long now?

haha yea I know, I was partial to pico 5, took me awhile to make the change to 6

[salvaje07]

I think thexton has an adapter to check the coil primary, but you could still hook a wire on the neg. terminal of the coil to see if its getting pulsed. If its getting pulsed, and not firing its bad. I have the sai2000, that works well on this system, but its pricey. The best tool for checking ign. is the low amp probe, ramping coils works well once you get a feel for it. But, you can have a good ramp, but the misfire can be happening after the coil windings, usually a bad connection internally. And on some systems you can hook up to the coil fuse (using a fused loop wire) and see all the coils at once.

[insanecheverolet]

I found that by using a back probe to the power ground at the icm will give you the above pattern, Is that how you are doing it?