I have an intermittent elecrrical issue that will drain my batteries to nothing over night at random intervals of time. This has been a persisting issue and I will chronologically detail what I've done thus far:

1. Come out to find van dead, charge up batteries and get load test; all good, maybe the cold killed it. Put em back in

2. Some days later, dead again. Pull, charge, start hunting down culprit. Circuit test shows radio circuit flashing, assuming the internal clock may have shorted. Great, disconnect radio along with my power amp, pat self on back.

3. Week or so goes by, dead again. pull, charge, sees that alternator couldn't really keep batteries up past 14 volts, I am usually at 14.5. Cool, pull alternator, replace with reman alt from parts store. System running at 14.52, excellent. Pat self on back.

4. Another week or so goes by, you know the drill lol. Replace big battery that still has warranty. No change. Replace companion that didn't have warranty, lo and behold it seems like we're getting somewhere.

5. 5 to 6 weeks goes by, here's where we're currently at at the time of this being written. go to start van and it is severely drained. My glow plug relay is like 14 years old so I go ahead and replace it just to see what happens. Crossing my fingers this helps, but signs tell me that it probably wasn't the culprit.

HERE IS THE CONDITIONS I KNOW THUS FAR:
1. The first drain happened right when we started getting our first nights into the 40s (Houston TX)
2. Running power to other things in the van seem to make the voltmeter draw down and wiggle a bit, I usually sit right past M solid but if I turn on my blinkers, lights, ac fan, or reverse, it will cause it to move a bit. Don't know if thats normal.
3. When the issue happens, the voltmeter won't go to its spot past the M no matter how long it is ran, more throttle moves it up but it drops right down after throttle is eased. I have to charge the batteries up with a charger fully to get the voltmeter to show it back in the right spot.
4. Van seems to run no different when these issues happen
5. The only other weird electrical issue I know I have is that my over drive won't turn off at the button, and the fuse has never blown.

I did my glow plug relay today before I made this post, but sometimes when I change something it looks like everything is going fine and then back to square one. Voltmeter still draws down turning more things on, and turning on as much as possible will draw it down even harder. I'm not a mechanic so I need some trouble shooting guidance and advice on this. Thanks in advanced!

 

The parasitic draw definitely could have been the gpr. If you still have it its easy to check with a voltmeter.
Jumper cables and a voltmeter is all you need to test the old one wo installing it in anything.
Let us know in a few days if you are still having the issue.

 

I suspect the alternator's diodes causing some if not all your problems here. Even with the reman'd part this could still be an issue--what brand is it or from where did you buy it?

You'll want to perform a rather thorough parasitic draw test once you know this isn't related to the alternator itself. Given your stated year there shouldn't be too many "smart devices/modules" turning themselves on and causing this draw. This video by FordTechMakuloco is one of the best to do this correctly: It does cover issues you won't have but its helpful none the less.

Good luck with this!

 

How about something basic like wonky door jamb switches or a loose visor mirror cover? Our ‘93 E150 had a loose visor mirror cover that would leave the vanity light on if the visor was left mirror side down. It wasn’t bright enough to tell from outside that the light was on.

Sixto
07 E350 5.4 178K miles