Ive been losing battery power mysteriously. Its a 99 2500 5spd 4x4. If it sits over 24 hrs, its completely dead. Both batteries are new, no change, cleaned cables and replaced ends, no change, removed grid heater and disconnected relayes, no change.pulled alternator, had it checked by 2 different shops and it checked out okay both times. I have removed the Tst box and harness, again no change. Any ideas what to check now?

 

well whatever it is its pullin alot of juice if its drainin both batteries in 24 hours. you wouldnt happen to have an audio system in it would you?

 

No not really, just a head unit and some newer speakers, no amp or subs or anything. Both the radio and speakers have been in for over 2yrs. Only thing I can think of is if the starter selinoid is draining them. Only thing I haven't tried yet

 

well i wish you the best of luck. i hope its nothin to serious.

 

get a D.C. amp clamp and place it around the positive cable while the truck is off. Make sure the amp clamp is around only one wire. If their are more wires on the positive cable check each one to see which one is drawing current. At this point you can start pulling relays and fuses from interior and exterior fuse blocks and relay stations. Pull and check amp gauge and keep pulling till it quits drawing amperage from the battery. This is the easiest way I have found to locate a key off drain. I had my fuel heater relay stick closed and caused my batteries to drain down and found the problem this way. Good luck.

 

Okay,ill try that