My ‘01 MC SS 3.8 security light goes on randomly. No codes. I’ve replaced the sender around the ignition switch, sorry I can’t remember what it’s nomenclature really is. But still get the light. I found a fuse blown for the door lock system and replaced it, I only found it after my trunk switch stopped working. Dealer says it could be the keys?
Any help would be appreciated.

 

Honestly doubt it's the keys. The keys for these cars are "dumb", just a piece of cut steel, no chip or anything. So if it is the key, then it means the key is actually worn down and cutting a fresh key (not a copy) would be the solve.

Does the car have any aftermarket remote start? If so, it could be a malfunction with the anti-theft bypass. I have a similar issue with my 2004 Grand Am (which has the same anti-theft system). I think it is my bypass for my remote start. I have tried reading on it in the GM Shop Book and scanning it with a GM Tech II scan tool and yet to find anything that helps.

 

Nothing after market. Brought an ignition cylinder and pass lock sensor to a locksmith, they said it was the security system. It’s what came on the car when I bought it new. Can it be turned off?

 

Turning off PassLock is a "fun" topic. As mentioned, my Grand Am (which is the same PassLock system as the 00-05 Monte) has been doing the same thing you mentioned yours has been doing. One kicker, I had a couple of times where it went into theft mode and I had to do the process with the key to kick out of that.
Now why I said disabling it is "fun". One method is to reprogram the PassLock system to a resistor. A friend Kyle in the Grand Am work has a good video on that with the Grand Ams (same process for a Monte). I have been dabbling with shutting it down in the PCM. I *might* have it shut off in my Grand Am (I cannot recall the last time the security light popped on). But I am not 100% certain and even though I offer some small PCM services, I am not comfortable offering this specific item because I am not 100% sure it works.