Quick Tip: Ignition Coil Current Ramp Test

When testing an ignition coil, it can be tested a few different ways.

One of those ways is a current ramp test.

So let's walk through how to do that on this Hyundai behind me.

All right.

To do this, we're going to use the guided component test function.

I already have the vehicle ID before, so I'm going to go into previous vehicles.

There it is right there.

And then we'll see the different systems we can test.

In this case, engine is where the coil is.

Then we see all the different components inside the engine system.

So we'll go down to where it says ignition coil and then we have component information and we have primary tests.

So we're going to do a primary test and that'll be that current ramp test right here.

So it says we'll use a low amp probe, connect the probe to the scope as shown.

We've already done that.

Automatically zero it and it says clamp the current probe around the battery positive side of the OR the control side of the ignition coil.

Do not clamp on both.

In this case we're around the battery side so all I got to do really is hit view meter and it'll open up automatically sets the scale for me, automatically sets the time for me.

Now all we need to do is start the vehicle.

So if you could start please.

All right, there we go.

Now we have a current ramp in here.

Now, you'll also notice, like I said, it has automatically set it up.

But sometimes you need to make small adjustments.

So in this case, we're going a little off the screen.

So I need to make it a little higher.

So I'll just come down here, change my scale from 10 amps, we'll change it to 20 amps, and there we go.

Now we can see it on the screen.

So I'll stop the recording and then we can shut off the vehicle now.

All right, so here is my current ramp.

Let me bring back the pictures here.

So we can see here's a nice smooth ramp up.

It does ramp up a little more sharply towards the end, but I think that's just due to the construction of the coil.

So we can see how it ramps up smoothly.

And then in this case it's it goes up and as soon as the coil would fire would be when that big drop off occurs.

Now if we look a little further on the background information, we will see there's what a known good one looks like.

Now in this case, it's a little bit different because this is what we would call a current limited coil.

So in this case, the manufacturer decided they wanted to limit the the current inflow to a certain number, whatever that happened to be.

So in that case you may see a flat top.

In this case it is not, it is just a kind of ramps up.

So it goes up kind of like a triangle.

So there's two, there's really two different types that you would see out there.

And then an example of a bad coil though would be right here where it goes up sharply at the beginning and then over and it says if coil waveform has a sharp rise at the beginning of the ramp, suspect a shorted coil winding.

So that's a good way to test and see how that coil is working internally by using this current ramp test.