86 Silverado LS1

iTrader: (2)

My 01 Yukon security light seems to have a mind of its own. When working properly what triggers this light and what does the security system do? I have seen other threads on this and I started one on a related problem but still dont have an answer. Anybody know what this thing does and why?? Thanks

https://ls1tech.com/forums/general-maintenance-repairs/823400-01-yukon-wont-stay-broke-long-enough-fix.html (my other post)

Camaro_Z28

The security light is the "trouble" indicator for the vehicle theft deterent system. This is the system that makes sure the correct key is used to start the vehicle. Its called the pass-lock system. It basically measures voltage drop through the pass-lock sensor that is built in to the ignition lock cylinder housing. if the security light comes on, it detects a fault that will still let the vehicle, but indicates that there is a fault. The most common problem I have seen is just a pass-lock sensor that is intermitantly throwing a code, and just needs replaced. Some faults will not allow a car to start at all, others will just set the security light and never cause a no start. The security system will store a code when the light comes on, so if you really want to get to the bottom of it, take it to a dealership and get the code out of it the next time it happens. Hope this helps