Your IS300 ignition coil is an external device that delivers intense voltage to the spark plugs in your 3.0 liter 2JZGE engine. When your 2JZ ignition coil starts to fail, there’s a few common Lexus IS300 issues you will begin to notice. Today I’ll be showing you how to test your ignition coil in your 3.0 liter 2JZ inline six engine.
This Lexus ignition coil shares many traits as the Toyota Supra and the Lexus GS300 counterparts. It’s connected by a two pin wiring harness and mounts directly onto your spark plug through your spark plug galley.
Symptoms of a bad IS300 ignition coil
Here are just some of the Lexus IS300 troubles you will have when this ignition coil starts to fail :
- Lack of Power
- Inconsistent shifting
- IS300 won’t start
- Long cranking time
- Engine misfire
- Check Engine Light ON
Of course one of the early warning signs is your IS300 check engine light. When you see your Lexus IS300 starts to show any of these signs, use a OBDII scan tool to retrieve your trouble code. One of the more common Lexus IS300 trouble codes include P0300.
If your Lexus IS300 check engine trouble code comes back as ignition related, you will need to test your coil.
To access your coils, you will need to remove your IS300 engine cover and intake system to access your spark plug galley.
There’s quite a bit to remove and disconnect before you can access your spark plugs. It’s not exactly hard to do but there’s a lot of work involved.
This How To Guide here can show you how to get to the coilpacks. In order to test your IS300 ignition coil, you will need to use a digital multimeter or ohmmeter.
Half of the battle is to get to your ignition coils. Once you have them exposed you can use your multimeter to test the coil function.
Undo the 10mm bolts that secure the IS300 ignition coil in place. Pull up gently to remove the coilpack, and you can begin testing.
Sometimes you will pull up on the Lexus IS300 coil and the spark plug boot will remain on the plug. If this happens you’ll need to remove the boot as well from the spark plug well. Because of the coil-on-plug design the heat may cause issues when you are initially unplugging your coil pack.
The first order of business is to measure the primary resistance of your Lexus IS300 ignition coil.
Test your Lexus IS300 ignition coil
Turn the dial of your multimeter to measure resistance Ω and put the leads on either pin of your ignition coil. Reference the IS300 wiring schematic below to see where to put the leads of your multimeter.
Don’t worry about which pin to measure with the red or black leads as polarity doesn’t matter here. Measure the resistance between PIN A and PIN B and you should see between 0.33 – 0.52 Ω.
If your 2JZ inline six engine ignition coil checks out here, move onto the next step.
Next you will be checking the secondary coil resistance, which is measured at the spark plug inlet and outlet.
To do this you will be placing your multimeter leads at the coil inlet and the outlet. When you have the leads at either point the resistance should fall between 8.5 – 14.7 kΩ.
If your IS300 ignition coil still checks out okay, it’s time to move onto your other ignition components.
You should also measure each one of your primary spark plug wire. Do this by putting either lead at the ends of each high tension wire.
The resistance here should measure between 10-20 kΩ with a maximum resistance of 25 kΩ in this wire. If the high tension wire checks out the next thing to check is your spark plugs themselves.
Use this guide to fix your Lexus when your IS300 is having a hard time starting. If your IS300 ignition coil falls outside of these testing parameters, it’s time for a replacement coil.
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