Will not start, possible Security System issue?

2002 GMC YUKON

240,000 MILES • 1.5L • V8 • 4WD • AUTOMATIC

WWLITTLE

MEMBER
1 POST

I am not able to start my SUV listed above (XL model). I think it is the security lockout system. Nothing happens when I turn the key. Initially, the "Security" warning light was flashing, even when no key was in the ignition. I followed each of the step's procedures on your post regarding this topic. Also, a lot fewer dummy lights are on after trying your procedures. The vehicle was running fine when we parked it. One more piece of info: our son got into some trouble, so there is a breath analyzer (interlock) device connected; however, that had been functioning without issue. The car had not been driven for a couple of weeks prior to trying to start it today. Thanks.

Bill

Apr 27, 2023 at 12:34 PM

STEVE W.

✓ASE Certified Mechanic
15,200 POSTS

If nothing happens when you turn the key, it isn't the factory security system. It disables the fuel not the starter, it will still turn over it just won't start. The first thing to look at is the battery. It could be low enough that it won't engage the starter.

https://www.2carpros.com/articles/car-battery-load-test

If the battery tests good, then I would look at the interlock next. Most of them disable the starter. I would also check the connections just to be sure they are clean and tight.

Image (Click to enlarge)

Professional Diagram for 2CarPros Members
Click here to log in and view diagram.

Apr 27, 2023 at 3:49 PM

Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.