i agree with the guy on top ^^^. my 09 srt8 isn't locking or unlocking with my remote. even from close or not. it takes me like 5 mins for it to get signal or something. i went to radioshack to test the battery in the remote, and no dice, the battery was working fine. i SOMETIMES get the "KEY FOB NOT DETECTED" but it isn't anything that happens all the time which is the weird part.
Don't test the battery, just replace it once a year. The battery will still test good and not reliably work the fob. It took me a while to learn this lesson. I kept testing batteries, cleaning contacts, etc and finally just changed all the batteries and no more problems. The fobs are very sensitive to battery voltage. The fobs with our Jeep are especially bad about being sensitive to battery voltage.
2015 Hellcat incoming - finally picked up 10/10/15
2009 Challenger SRT8 - gone
2010 Jeep GC SRT8
11 GMC Sierra Ext Cab, LB
69 Pontiac Grand Prix 428