Lack of check engine light

I've always passed California smog with no issues, but this time failed because my check engine light doesn't illuminate in maintenance mode. Looking back, I can't remember whether I have ever seen my check engine light turn on. I bought my car from a questionable seller 5 years ago, and I wouldn't be surprised if they somehow tampered with the check engine light. Does anyone have suggestions about where I should check to see if they disconnected it? I know that in the Gen 3s the check engine light is an LED, so they couldn't have just unscrewed a bulb. Maybe they snipped a wire? Does the check engine light plug into the ECUs behind the glove box?
Thank you for any advice.