How To Test a 420A Coil Pack

How To Test a 420A Coil Pack


The DOHC 2.0 liter non turbo engine found in the 1995-1999 Mitsubishi Eclipse, Eagle Talon, and Dodge Neon is also known as the 420A engine. When you have inconsistent spark issues, or you are trying to track down ignition misfire you need to check your ignition coil packs. Today I will be showing you how to test a 420A coil pack using a multimeter.

Today’s test vehicle is a non turbo 1997 Mitsubishi Eclipse. This vehicle is equipped with the Chrysler 2.0 liter engine, and I’ll be showing you how to test the coil packs.

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The way to test your 420A ignition coil pack is to measure the internal resistance. Need a guide on how to use a multimeter? Check here for our guide. Before doing so you need to check for spark at each spark plug. To do this part of our How To DIY test, you will be inserting a spark plug into the HEI wire and resting it against your valve cover to check for spark.

As always use extreme caution when working around your vehicle. Use our safety tips to make sure you are safe. Your 420A ignition coil unit can produce upwards of 40,000 volts. Personnel injury could result from contact with this system.

How To Test a 420A Coil Pack

Check for spark by cranking over your engine. Make sure that all four wires are receiving spark by checking the plugs one at a time. If you do not have any spark, check your crank angle sensor and your camshaft position sensor first.


If you have spark at all four spark plug wires, you will now be checking the internal resistance of your 420A Coil Pack.

How to Test your 420A Coil Pack

To begin testing your 420A ignition coils, open your hood and locate your 420A coil pack. It’s mounted to the top of your valve cover. Now unplug the wiring harness to expose the three pins of the 2.0 liter ignition coil pack.

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Take your multimeter and put it into OHMs mode, and you will be measuring from the power pin (B+) to the 2 sides of the coil pack. Put one of the leads of your multimeter to the center pin, and measure either side of the coils.

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As the 420A ignition coil wiring diagram shows above, PIN A is responsible for cylinder 2 and 3. PIN C drives cylinders 1 and 4. Measure the internal resistance between the B+ pin and either PIN A and PIN C. The resistance here should be within 0.51-0.61 Ω.

If your 420a ignition coils do not return an internal resistance within this range, you need a replacement coil pack. Does this part of your test check out but you still have a ignition misfire or high RPM spark blowout? Move on to the secondary test for your 420A Coil Pack.

How To Test Secondary Resistance of a 420A Coil Pack

If your primary test checks out okay but the misfire in your Mitsubishi Eclipse, Dodge Neon or Eagle Talon still persists, you’ll need to complete this check. In order to test your secondary ignition coil resistance, you will be checking from one side of your 420A coil pack to the other.

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Put either of the multimeter leads on the spark coil pack leads as shown above. Pair A is for cylinders 1 and 3, while Pair B is for cylinders 2 and 3. Both sets should return a resistance value of  11.5 – 13.5 kΩ.

Same as before if these values dont’ check out in your ignition coil pack, it’s time to replace it with an OEMSPEC unit.

Have any questions about our 420A Coil Pack How To DIY article? Leave us a message below and let us know!