Key fob lock button not working

[Aspen273]

Hi everyone, I have a 2015 Gmc Serria SLE double cab with a key fob issue. 

 

ISSUE- The key fob LOCK button will not work. All other buttons are working, unlock and alarm (obviously I'm not sure about remote start because lock button must be pressed 1st). 

 

TROUBLE SHOOTING-

1- checked all 4 doors and hood to ensure they were closed.  

2-replaced key fob battery

3- checked to make sure button was actually being depressed on circuit board.

4- Checked button contacts with multi meter to ensure button was actually functioning. 

 

SIDE NOTES- 

All lock buttons on all 4 doors are functioning WITHOUT issue. 

I've checked all vehicle settings pertaining to locking and keyfob and all look OK. 

I'm not getting any warning, cautions or messages from the truck that would make this happen. 

Any help would be greatly appreciated! 

[Jsdirt]

Impossible to know without a scan tool. When you press the buttons that don't work, you need to be able to see if the BCM is receiving the input signal or not. If the signal isn't making it to the truck, it could just be a defective key fob in that case.