Weird start and no start

[06DieforDiesel]

so got in my truck this morning around 8, pretty cold outside but not freezing, warmed it up and started like a champ. a few hours later around 12 oclock i went outside to start it again and go to lunch, so i warmed it up and tried to start it, heres the problem...
it wouldnt even try and start. it made a bunch of clicking noises and all my gauges freaked out and started twitching. i tried 3 or 4 times with the same results. about 5 mins later and a whole lost of cuss words i tried again and started with no problem and drove fine.
what the hell was that?! i didnt think it was my batteries cause everything was fine this morning after sitting all night. i know this probably isnt it either but i did remove my CAT yesterday (so maybe the CAT?)
could it be alternator or starter or what??

please help

[thomaslord84]

Well the clicking to me sound like starter or relay, but the gauges going crazy IDK what would cause that.

[fixxxer-upper]

I had the same issue when the alternator was acting up. The batteries weren't being charged during normal operation. With low input voltage, the PCM will shut down power.