I have a 99 suburban.w/ remote start. remote start works. door locks will not work from the key fob. locks do work with door switch. Likewise the interior lights work from the switch on the dash but not when the doors open. Are these 2 problems related? What steps should I take to remedy these problems?

door switch inside the lock mechanism is probably bad. You say the remote control will remotely start the truck but the keyless part doesn't work? Do you hear any clicking when you press the buttons on the keyfob