[G-Rod7.3]

Im in dire need of some expert advice. My 2001 F250 7.3 has a charging issues. I first got my truck back in Dec. and i loved it, it has 130,000 miles or so but in great shape. I followed the advice of others and didn't mod it for a while just appreciated what it was, then i opened up the wallet. It runs sweet and she's pretty quick for a 7,000 lb truck. Now down to business, i had personally put about 4,000 miles on it since ive owned it. One day my charging circuit idiot light came on while cruising down the highway and i'm thinking oh crap alternator is done. No... the voltage holds steady on the gauge at 13-14 volts and continues to do so for 100 miles. At home i pulled the alternator and sent it to autozone for a test... amazingly they say pass. Back at the house i pull out the old owners manual for fun and started checking fuses voila i see a fuse in the engine compartment in position #7, a 5amp fuse responsible for alternator field current. Hmmm... i replace it put alternator back in and 5 min. down the road charging light back on blew out fuse #7 again. Okay so i figure it has to be the voltage regulator in the alt. So i buy a new one. Guess what no charging lamp for atleast a solid month untill today. So now im mad i blew four fuses today (same #7) and i don't know why. I hook up the ol' multimeter and start poking. To my surprise the alternator is putting out 14.39 volts with the fuse blown, if i put one in the alt. is charging at 14.12-14.18, isn't this odd why does it charge higher with blown fuse, the batteries are reading in the 14's as well with or without a fuse what could cause this? I know its probably not good put i stuck a 7.5 amp fuse in place of the 5 amp. Any thoughts... Anyone?

 

[tinman13kup]

A few things to check
fuse 6 AND 7 go to the field. They are in series, 6 first (10A) then 7 (5A) then on to the alt.

- Check for 12V on the LG/R wire. That is the idiot light circuit, which is connected to a fuse under the dash. When the alt isn't charging, it (volt reg) applies ground to that wire to illuminate the batt light. If that wire is shorted to ground somewhere it will also light the batt light. In other words, there is normally 12v on both sides of the idiot light, so no light. When the alt voltage drops, the internal circuits change that 12v into a ground and turns on the batt light. Clear as mud yet?:lol: