I had to replace a keyless remote for my 2001 dakota. I found one off od E-bay then I had to program it using the programing sequence in the owners manual. It was really simple. I only paid something like ten buck for the remote and have had no problems.
the dealer does it with a scan tool
Open the keyless remote and you will see the battery take it out and replace it with the same size.
I had the same problem. Google "keyless entry remote 2003 Jeep Grand Cherokee".
Possible weak battery in the remote.
You have to program it with a DRB (Scan tool).
centre top dashboard (red dome)
dealer has to do it with factory scan tool
replace the remote
Try the mirror control.
Most of the time all you need to do is replace the battery. If it doesn't work after that, you will need to take it to a dealer.
It was optional.
it has to be done by the dealer. =(