I own a 2006 Silverado 1500 LT and I noticed that the key fob does not lock/unlock the doors. The power locking works with the passenger side buttons (drivers side switch is broken but lock still works). The key fob flashes the lights when the lock/unlock button is pressed but does not actually work. The key fob works for remotely starting the car, so I don’t think the fob is bad. I do not know where to start troubleshooting.

 

My similar experience it was the driver's door switch. Don't buy the cheap ones, they don't work, get at least a Dorman, I found out the hard way, bought a $20 amazon one and it was a no fix, bought an AC Delco and all the issues went away.