I have an 98/00 Ram 1500 5.9L Battery drain overnight. Pulled fuse 12, lost radio, pwr mirrors and interior lights. Truck ran great, no drain. But,,,the OBD connector also had no power, and the ECM reset, gives an O2, CT sensor errors.I have an OBDII tool. {still no CEL} Took out radio, disconnect mirror controls and left window power, still have a drain. So, found the top brake light on the shell had blown, removed it. Still this issue. Can jump truck, and will run great with fuse 12 in, but still a drain. NO fuses are blown! CEL not on, and I cannot get a smog check done, because of all this. I have the Haynes manual, but the wiring schematics do not show what all is on this fuse! thanks for any advise!

 

So do you have two trucks with the same problem? There are a fair few differences between 98 and 00......

 

Sorry, it'a an LLBB 98 rebuilt at Dodge factory I am 3rd owner. Pics in manual do not jive with what I have in fuse boxes.

 

You can get service manuals here. Grab both, see which one fits.

 

I have them both, do not say what all is on that circuit. Have taken five items out of the loop that quit working when I pull fuse 12. Put fuse in, still drain. Battery and connections all ok.
Could part of the ECU be the short? Fuse 12 also gives power to the OBD connector under the dash.

 

Wouldn't hurt to check the wires down there, make sure nothing is shorted.....