So I can't figure what is wrong with my key fob. I got a new one because the old board wasn't so good after a while, it worked for a little and then changed the battery on it, now it won't even unlock/lock the car. It'll register with the factory radio, but it won't do anything to the car. I took it to autozone and it passed the test so I dont have a clue. I read somewhere on the internets that I might have to have the PCM cleared of the FOB controllers or have it reset?

 

First, your new fob, are the ID numbers on the back of it the same as the original one? From what I understand, that is required to make the fob work with the car. I don't know much about the "why". I speculate because even though it may program, perhaps the signals for the buttons are not compatible signals for the car (I'm guessing).

Second, when you go into fob programming mode via the radio, the moment you successfully re-program a fob, all others are deleted (this is why the shop book tells you to have all new and old fobs ready when you go to program a new fob). Also, at least for our generation Montes (00-05), not even a GM Tech II can erase the fobs in memory. Since I installed an aftermarket keyless entry with remote start into my wife's Impala, I was trying to get her one and only factory keyless fob removed from her Impala and programmed on the Monte. When I had a friend with a GM Tech II program a different radio into the Impala, I had him try to erase all fob programming in the computer, it can't be done. Also, in goofing with fobs, at one point, I had one fob that controlled both the Monte and the Impala (kinda funny in a way). All I had to do to stop that was reprogram only my original Monte fob (and not the wife's Impala fob) to the Monte (it wiped out memory of all other fobs).

I hope I did not confuse things with my explanation and back ground.