How To Service Your RB25 Ignition System

How To Service Your RB25 Ignition System


So you’ve got your RB25 or RB20 engine swap completed but your spark is giving you some issues. Testing your RB25 coil and ignitor are two jobs that can be performed very easily, and we’ll be walking you through in our how to service your RB25 ignition system writeup.

Before you begin your work, disconnect your factory battery in the RB swapped vehicle. Once your negative terminal on your battery is disconnected, you can begin your work of removing your RB25 ignitor and RB25 ignition coil for testing.

If you still have the factory intake manifold equipped, take off the charge pipe that leads into your throttle body.


With this upper pipe disconnected, you can now access your spark plug valley and the factory ignitor, if it’s mounted to the stock location. If you have upgraded to a front facing intake manifold on your RB25, this step is easy in our how to service your RB25 ignition system writeup.

The stock mounting location is the 4 bolts on the rear portion of your RB25 spark plug cover

To begin testing your ignitor on your RB25DET, unplug the unit and get out your voltmeter.


Here is the RB25DET ignitor that has six pins per side and controls your coilpacks, part number 22020-97E00. To test this unit get your voltmeter out and test the pin combinations shown below. There are two sets of plugs that connect to this power transistor, one from the engine loom and the other leads to your spark plug coil packs.

The E harness shown below is the plug that leads to your RB25 ignition coil packs but connects to your ignitor first.


The harness from your ignitor that goes into your RB25 coil packs is a seven pin unit and it’s shown below. The seventh pin in the middle of this plug is a ground on this setup.


To test your RB25 ignitor, take your voltmeter and test the resistance between the unused plug on the engine loom side, and the six pins on that same plug.

This should generate a resistance value of + / – ∞ Ω & – / + ∞ Ω between the seventh pin circled below and each one of the pins that leads your ignition coil packs.


Once you’ve tested this plug you can move onto the next thing to test, the ground ( your middle pin on the ingress plug ) going to each one of the pins on the opposite plug leading to your coilpacks.

Measuring the seventh pin with your voltmeter, test each one of the wires leading out of the six pin egress side of your ignitor plug.


The resistance values you are looking for here between the MIDDLE pin on the ingress plug and each one of the spark plug wires on the egress plug are + / – ∞ Ω > – / + 0 or not ∞ Ω.

And the last step to testing the RB25 power transistor on our how to service your RB25 ignition system article, is to replace your ignitor if any of these values are out of range.

Here is the specific schematic in question but the pin location of E3 is not correct at all, this pin is actually the MIDDLE pin on your plugset. This plug is not used when converting a 7 pin to 6 pin, and likewise will need to be wired when going from 6 pin to 7.


Next up we’ll be looking at the coil packs in our how to service your RB25 ignition system article. If you find yourself having problems with your RB25 coilpacks, we would recommend taking a look at How To Upgrade your RB25 coils article.

To test your coilpacks it’s just a one step process in our how to service your RB25 ignition system guide, just remove the coilpack and connect your voltmeter to the middle pin of your coilpack. Make sure to ignore the diagram above in reference to the ground wire, this is the black wire in the middle of your seven pin connector.


The other connection should go straight to the bottom of the coilpack, giving you a resistance value of 0.6 and 0.9 Ω. Once you test pin 1, move onto pin 2 which is the left most connector when looking at the coil pack straight on. This should provide a similar resistance value, but in the case it doesn’t you will need a replacement coilpack.

Consider our How To Upgrade your RB25 coilpack guide, because we give you a few coil options to look at, and don’t forget our How To Install a J30 ignitor. That does it for our How To Service Your RB25 Ignition System article, please let us know if you have any questions or comments.


  1. […] As it's spec 2 yes you can skip number 3, the spec 2 has the igniter on plug, so your coil packs has this built in. The testing of pins 1 and 2 is for the coil windings, you put the earth / black cable from your tester to the spring / output of the coilpack and test pin 1 and then the same for pin 2. You are looking for the same range on both winds 0.6 ~ 0.9 Ohm. There's an article on servicing the ignition system here […]


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