Doors lock 3 seconds after key is turned

[FoxDen]

I have a problem with my 05 Tahoe. When you turn the ignition to on (vehicle does not have to necessarily be started), all the doors lock about 3 seconds after the key is switched. I know about the settings to change with the locks and have gone through all of them. I have not had it to the dealer yet because I have a feeling there is a setting I do not know about. Thanks for the help in advance.

 

[OmarR]

Has the truck had previous owners?

If you can turn the key all the way, without the engine running, and have all the doors lock, I would almost be willing to bet that you have some kind of aftermarket unit installed. It could be a doorlock module, or even an alarm module.

 

[FoxDen]

Thanks for the advice Omar, I'll have to delve deeper into the situation I guess. I haven't noticed anything aftermarket I guess as the clicker and all that are OEM.

 

[DenaliAK]

I was thinking the same thing. My alarm arms itself automatically if you don't, although there is a longer interval then 3 seconds. I don't know about the locks, though, since I have mine set to lock anyway.