Alarm Randomly Goes Off - Theft Attempted

Lsgun1 · March 25, 2020

2018 Sierra SLT 5.3 6 speed - So a few times I've unlocked or tried to remote start the horn honked 3 times and I got a "theft attempted" message. Truck was not attempted to be stolen as its happened in a private parking lot and in my drive way. Yesterday the alarm decided to go off 3 times, again no one was around and the keys weren't even in the same room as me. I am not getting any door/hood ajar messages when driving or anything, no aftermarket electronics besides AMP powersteps with the OBD harness so no door wires were tapped. Did a search and not much comes up or there's no follow up to it. Don't want to bring to the dealer to get a "we can't find it" until I can duplicate or test something. Ideas? TSBs?

Ozer · March 25, 2020

My 2014 used to do it, ended up being a ground issue. Older battery also can cause this, voltage drops and causes all sorts of gremlins.

Being its a 2018 i wouldn't think its the battery but cant be sure.

Lsgun1 · March 25, 2020

Got a theft message again this morning after my original post. Unplugged the AMP steps from the OBD connector to try rule it out.

Lsgun1 · March 25, 2020

Well the alarm just went off again with the steps unplugged so that rules them out. Looks like it's the trucks fault and will be making a trip in.

JimCost2014 · March 26, 2020

2 hours ago, Lsgun1 said:

Well the alarm just went off again with the steps unplugged so that rules them out. Looks like it's the trucks fault and will be making a trip in.

Have your battery checked out.

They do not last long from the factory, or disconnect it for 30 minutes or so, hook it back up and see what happens.

Lsgun1 · March 26, 2020

Battery was 12.2v this morning at resting voltage with 30 degrees ambient. Guess I will have it load tested, frankly I would be happy if it turned out bad and that solved the issue.

Snowcamo · March 26, 2020

Yeah load test it. Batteries can show 12v and still have bad cells.

Lsgun1 · March 26, 2020

Well the truck decided to make my life easy and finally displayed the hood ajar warning when I started it this afternoon. Obviously the hood was not open and I also got the theft attempt message so instead of going to the dealer it’s $25 shipped off eBay for an OEM latch so I went ahead and ordered it. Unplugged it for now so if it doesn’t go off tonight then it’s

Lsgun1 · April 1, 2020

Put new latch in monday and have been good to go since. Just know if you unplug it to keep your alarm from going off you will get an engine light so don't panic when you see it.