2000 silverado key fob programming issue

[prospectivebuyer]

Simply, when i try to cycle and put in programming mode you can hear the switching but locks are not locking and unlocking. I have a fob from a split 99 that i was trying to use just to see if a new fob will work but I ran into programming issue. Not 100 if fob is working but the lack of locks engaging has me wondering if its going into programming.

[rjgti]

two dif fob's for that year, one will work, one won't.  how are you entering programming mode?

[prospectivebuyer]

Unlock down drivers side with two turns of the key to ignition and back. I can hear a click click but no lock movement.

[rjgti]

how do the locks work in regular mode. I have one that is weak in the winter