I recently bought a 2005 suburban and had no idea it had remote start until I accidentally held the lock button on the key fob. After playing with it for a while, I found out if I quickly press the lock button twice and then hold it down on the second press, sometimes it'll remote start, sometimes it won't, but that's probably because I'm not doing it right.

Does anyone know what the right sequence is to remote start it? I read on a forum post here that GMT800 vehicles do not have remote start, that'd imply that I must have an aftermarket unit. It still uses the default key fob that came with the vehicle, it just seems to be some combination of hitting the lock button the right way.

 

I figured it out in case anyone else runs into this issue. You press the lock button 3 times quickly on the FOB and it remote starts.

 

You have an aftermarket remote start system. GM did not offer remote start in those years. Only started with the 2007 GMT900 platform.