If your car won’t start and you can’t figure out why. You’ve checked that there is spark, the fuel pump is making its customary whirring noise when you turn the key. You pulled out the spark plugs, but they don’t look wet or even smell of gasoline. There is a gadget that you can check if the fuel-injection brain is working without buying an expensive scan tool?
A device called a noid light can be used to check to see if the injection system is working at all.
It’s simply a small incandescent bulb in a socket with pins that plug directly into the wiring harness leading to your fuel injectors. You can buy a set to fit any number of applications for as little as $15. Pop the connector off the injector and plug the noid light in. Crank the engine over. If the noid light flashes, the computer is operational enough to send voltage to the injector.
It’s a lot easier to see the noid light flashing eventhough you can also use voltmeter to read the reading.

Click here to read from the source.
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is noid light used only for fuel injectors of specific makes like ford and gm, i hop it also for asian and european makes like kia, hyundai , vw …..etc