Keyless remote, I can unlock my doors using the key fob but cannot lock them?

Most of the time the button on the remove goes bad. I would try a new one first. here are the wiring diagrams for the locks so you can see how the system works, also we can do a CAN scan to see if the BCM is bad which can cause this problem as well. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is a link to a new remote which you can program:

https://amzn.to/3CCNM9d

Here is how to change the BCM out as well in case you need it, you can get a preprogrammed unit by searching Google or Ebay. Check out the images (below). Please let us know how it goes.

Thanks for letting us know, we are here to help, please use 2CarPros anytime.