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Quick Tip: Alternator Ripple Test

Last Updated: June 4, 2021


Having a hard time diagnosing vehicle electrical issues? In this Diagnostic Quick Tip, National Field Trainer Jason Gabrenas shows you how to make it easy, checking the alternator using the Alternator Ripple Test.


Video Transcript


One of the more powerful features inside the Guided Component Tests and all of our lab scope products is this thing called a Top Level Menu.

It gives us all sorts of tests, tips, and maybe some power user tests that are a little more advanced than the ones that we already have within the tool.

Today we're going to talk about an alternator ripple test. This should be one of the first things you might want to do if you suspect you have an electrical problem in a car.

If they have a bad alternator or it's putting out some sort of weird pattern, it's going to screw up all your diagnostics, so it's a good place to start.

So I'm going to show you how to get in there. All right, so in order to get to this test, we're going to have to go into the guided component tests and then we're going to click the menu button here on the bottom. 

Go to Top Level Menus and How To, then this test is under test tips and it's the very first thing right on the top. It says alternator ripple tests.

We're going to to load up, and we'll see here in the second section it says here's how to hook it up, plug the yellow to the alternator output and the black to the battery positive. So that's how we already have it hooked up over here on this car.

So I'm going to scroll down a little bit further and see it gives us a few indications of what a good pattern looks like. Scroll down a little more, it even shows us a bad pattern.

So I'm going to click view meter here, should pull up my meter and then I'm going to go over and start the car and see what the alternator looks like on this vehicle. 

All right, so looking at this pattern, if we compare it to the patterns that are above here, we have a known good pattern and a known bad pattern.

Other than a little bit of noise going on here, we do have an overall good pattern. You want to see nice, even bumps going on there.

Now on this bad pattern here we see a few bumps and then something drops out and then we see a few bumps and then something drops out. That indicates an issue in the alternator winding somewhere.

So this is a really good place to start your diagnostics, especially if you think you have an electrical issue going on in the vehicle.

Because if you have a bad alternator, you might be brought down the wrong path and you wouldn't want to waste any time there.

Applies To

MODIS Edge, MODIS Ultra, TRITON-D8, Vantage PRO™, Vantage Ultra™, VERDICT™, VERUS Pro, VERUS™ Edge, ZEUS


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