How To Test a 2JZGE Main Relay

How To Test a 2JZGE Main Relay


Part of troubleshooting a 2JZ that doesn’t start has to do with the EFI system or EFI main relay. The main relay is a crucial part of your 2JZGE charging system and allows for your ECU and sensors to receive power. If you have swapped a 2JZ into another vehicle, this relay is the one you’ve got to get right, luckily it’s a very easy thing to test.

We’ll be showing you How To Test a 2JZGE Main Relay in a 1997 Lexus SC300 with the 3.0 liter non turbo 2JZGE in it.


If you are having problems with your 2JZGE starting, you can often be faced with nothing but the gauges blinking back at you when you try to start your car.


Although we’ll be showing you how to conduct this test in a SC300, the testing procedure is the same for a non turbo Toyota Supra or IS300 / GS300.

Where is my 2JZGE Main Relay Located?


Your main relay is located in the engine bay fusebox located above your battery. Because the SC300 is equipped with just a single battery negative chassis ground, testing this unit is crucial to resolve 2JZ no start situations.


To begin our How To Test a 2JZGE Main Relay Guide, open your 2JZ fusebox and remove your EFI Main Relay. Flip the relay upside down and you should see four terminals labeled 1, 2, 3 and 5.

You will be using a multimeter to test the pins for continuity to see if your EFI main relay is any good.

How To Bench Test your 2JZ EFI Main Relay


To being the inspection process, use your multimeter or ohmmeter to check for continuity between the terminals labeled 1 and 2. There should be continuity here at these two pins, once you have checked these two pins, move onto terminals 3 and 5, which should have no continuity.




If you get any results that fall outside of those specifications, your 2JZ EFI Main relay is bad and must be replaced. The common Toyota part number for this item is 15670-00060 or 28341-11010. This relay can also be found in the Lexus flag as 90084-98009 or 90987-02010.

If these fail, you can always opt for the GM version of this EFI main relay, which would be part numbers 94853220 and 94854542 respectively.

Powering your EFI Main Relay


Next in our How To Test a 2JZGE Main Relay article, we’ll be checking the 2JZ EFI Main relay by sending power to the terminals in order to activate it. You will be in essence simulating the same action that should occur in your 2JZGE when you turn the key to the “START” position.

If you have a device that is capable of sending power and ground to terminals, now is the time to use it. If not wires with butt end connectors will do fine. You will be sending battery power to the terminals 1 and 2 on your 2JZ EFI Main relay.

With power applied to pin 1 and ground applied to pin 2, you should hear or feel the relay click over. If you do not, check for continuity between terminals 3 and 5, there SHOULD be continuity here with power and ground applied to pins 1 and 2.

If your bench test of your 2JZ EFI main relay fall outside of these parameters, it’s time for a replacement EFI main relay.

Congratulations, you now know How To Test a 2JZGE Main Relay. Please leave us any questions or comments below!

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