Check engine light NEVER comes on

Instead of possibly wasting time removing the cluster I suggest you first try grounding the lamp pin at the ECU. If the light turns on then you have proven the trouble is inside the ECU. If the lamp doesn’t work then you need to check out the lamp circuit wiring further. One side of the lamp leads should tie to power through the ignition switch and the other side ground through the ECU.

UPDATE - Problem solved!!!

Nevada you were dead on right!!! I finally pulled the glove box out today to have a look at the ECU. At first I didn’t see anything wrong. But as soon as I pulled the top connector off, there it was. The Green/Red wire had been snipped.

I decided that the simplest fix with the lack of space was to crimp spade connectors on. Problem solved.

Now I have light.

The best part is in came on like it should then went out after i started the car. My father in law took his scanner back so I am getting one next week and replacing the o2 sensors as im sure they are original.

Thanks again to all the responded, and especially to Nevada who was dead on.

Someone pulling a fast one, huh? :slight_smile:

Sounds like a good idea to me…The spade connector gives the owner complete control over the nag light…

Maybe a toggle switch…??? :slight_smile:

I have a 2000 Miata check engine light will not come on. Someone took out the cadalic converter so I presume they disconnected the light but is miss firing and running bad no one will scan it as the light is not on I don’t care about the light I would just like to know why it’s running rough if I buy a scanner will it tell me anything or does the light have to be onl

The scanner should still work and retrieve error codes, even if the check engine light isn’t on. The scanner reads the computer trouble codes. The light is just there to tell you the computer senses a problem. Now if the check engine light is not on, and it isn’t supposed to be on, there may be no error codes for the scanner to read. But if that were the case, the car would be running fine. So I think you’ll get some codes when you hook up the scanner.

If the CEL dash bulb is burned out then it won’t come on with the key in “on” and the engine not running. In that case there may be diagnostic codes stored in the computer’s memory. If it comes on with the key in “on”, but goes out and stays out once the car is started and the engine running, that means the computer isn’t detecting any problems. Doesn’t mean there aren’t any problems, just the computer isn’t sensing anything is wrong. For example if you had a little water in the gasoline, the computer might not be able to detect anything wrong, but you’d notice the engine wasn’t behaving normally.

Why on earth would you even think changing the oil would shut off a CEL?

Darn it got caught on the years old thread thing again.