99 tahoe keyless receiver module

Help !! :banghead:

I have a 99 Tahoe and the keyless quit working. I have a brand new transmitter with a brand new battery and followed the programming instructions. At best, the keyless works very intermittantly. I have done the program procedure 5 times and get the same result. I think the module may be bad. Where is it located? Does anyone know??

Thanks

Ivan