I've got a 94 f-350. A couple of times over the last two years, I would come out in the morning to start my truck and the batteries were completely dead... I'd jump the truck, charge the batteries, and everything would be fine. This has only happened twice in a couple years but I'm afraid it will happen sometime it's very inconvienient...

I suspect there's a sticking relay somewhere that is draining the batteries. It has to have a reasonable load since there are 2 batteries and it drains them completely overnight.

Has anyone had a similar experience or have any insight into what might be the culprit?

Thanks for any suggestions.

 

Same here

 

I would start by isolating one system at a time to find it. You will need an amp meter and a good set of electrical drawings for this. Shut everything off in the truck and then use an amp meter to monitor any drain. Isolate one system at a time. When the current stops, the last thing you unpluged is it. Replug it in to confirm. Repair that part.

 

If it happens so little I doubt you will find it easily. Probably something crazy like the brake lights are sticking on every once in a while.

Does it have an aftermarket stereo or driving lights?

Think real hard, was there anything in common that was going on when this happens?

If you do not find it before it happens again, look at everything electrical on the truck when you hook up the jumper cables. You should be able to find something on that should not be on.

 

Yep, since it's so infrequent, troubleshooting is very difficult. It's a good idea to try to see if something's on the next time it fails. I will hook an amp meter in between the jumper battery and the truck to see how much is being drawn. There certainly wasn't anything like headlamps or obvious large draw left on the last two times it has happened.

I have no extra, 3rd party, gadgets that I could point my finger at.

One more thing. A few weeks ago I started the truck, started driving, smelled something electrical, and the engine quit. Fuse 11 which controls the glow plugs, fuel pump and other things was blown. I've replaced fuse 11 and it runs. My suspicion is one of the fusible links has burned up and blew the fuse but I haven't been able to find the location of the fusible links. I've tried to pull the glow plug leads and check continuity back to fuse 11 but have trouble getting any access to most of the glow plug wires without pulling a bunch of stuff off the engine.

I don't know if the above is related to the battery going dead but, if a relay left the glow plugs heating, that would kill the battery pretty fast...

Thanks for any suggestions.

 

That relay would burn out the gp's the 1st time it stuck on.I had a problem like that,turned out after much searching that every now and then the glove box light was staying on(too much junk in there).Disconnect one batt and then remove the neg cable from the other,tap that neg cable to the neg post and see if there is a small spark,if there is then you have something dragin on the batt,then pull the fuses one at a time,checking that cable for spark to find the culprit circuit.Good luck.