Door ajar lite comes on and the alarm keeps dinging all doors are in line and closed how to make the ding stop?

You must find the faulty door ajar switch that is causing the false signal. The warning comes from a module and it can't be disabled.

your door switches are probably dirty spray them with wd40 then scrub them with a tooth brush

You mean the door ajar alarm ?
You could probably pull the fuse for the interior lights to make it stop.
Chances are one of the door sensors has failed.
The PSD fuse is for the power sliding doors.

I HAD THE SAME PROBLEM WITH MY REAR DOOR TAHOE 2001 ., I TOOK IT TO THE MACHANIC AND IT WAS SO SIMPLE A FUSER UNDER HOOK . $8.00 FUSER ., IF I WOULD IT KNOW . I WOULD IT DONE IT MYSELF.-- REPLACE FUSER WHERE IT SAID --HORN- ITS UNDER THE FRONT HOOK... I END IT UP PAYING $120.00 FOR THEM TWO HOURS WORK...THE LIGHTS AND THE ALARM WAS NON-STOPPING MAKING NOISE..... RIGHT..????

there is a switch on the door frame the door hits this and brakes the turns the light and door chime off, will need cleaning or replacing.

you have an open door, if all your doors close theres a door switch that on on indicating an open door, or door switch wire shorted to ground

This means one of the door ajar sensors is stuck. You need to remove the door trim panel and then the latch and then the sensor. Once out clean and lube it. There is a sensor inside every door.

check the little rod that sticks out the door jam and make sure its in the proper spot if it got knocked somehow it could be closed but it doesn't know it and will ding

you may have a broke wire in the door harness

ok, if the sensor for doors is inside door latch, just sparay some lubricant like wd-40 or something similar to the door latches and keep opening and closing doors until problem fixed