I have a bizarre electrical problem and can NOT figure it out. I'll be driving at any given time and the check gauge light will come on and bing. Either the Fuel gauge is cutting in and out or the battery charge is fluctuating from about 10v and goes back up to proper charge at 14v. The only code it ever kicks is battery temp sensor. I have changed the batt temp sensor 3 times (twice with NAPA part once with Dodge part) with no change. I have changed the fuel sender/pump in the tank with no change. Batteries are good. Had alt test-good. Very humid days seems to make it worse that other days. So I've pulled every connection I can find and cleaned it and greased the contacts. Sometimes it won't happen for so long that I forget it's an issue. Sometimes the check gauge light dings so constantly its like the door is open while I'm driving...
No it's not the grid heaters kicking in, and I know it's not actually the batt temp sensor (happens winter/summer/rain/shine). I doubt it's the ECM since this is the ONLY problem the truck has or has ever had. I have also run the gauge cluster self test and it's OK. I'm just thinking there must be some obscure connection I'm missing or a best kept secret of a rubbing wire. Battery connections/grounds are all perfect with new soldered lugs on grp 31p batteries.
....help

 

Check the positive wire from the passenger side battery that runs across the front of the truck to the other battery. There have been cases of it rubbing and shorting to ground on the engine.

 

I checked the cables all quite well when I changed all the ends to lugs. No short there.

 

There was a tsb for 05/06 that dealt with changing the temp difference allowed between the battery and intake+coolant sensors before it would set a code and CEL. TSB 18-005-06 REV. B

Don't know if it could be applied to your truck.

When I had an 03 I think I also had a TSB done about goofy gauge readings.

 

Well I didn't really want to go to the dealer but I suppose I have to go anyway at some point for the airbag recall. I could ask them I guess...where can I find a complete list of TSBs? I couldn't find anything very helpful when I searched it. Just a bunch of causes with no detail (ie Cummins PCM flash-no details as to flash WHAT). I wouldn't want them to change something else by either mistake or stupidity.