Hi,

I've been having lots of trouble starting my 2005 6.0L F250 lately.
So I figured, I'd check for a parasitic current draw.

I unplugged negative on the driver side's battery, plugged in a multimeter on the 10amp setting between the post and the cable.

Unplugged the passenger side battery negative. I have a draw of 0.88A!



I figured I'd unplug fuse by fuse to find the culprit.

When unplugging Fuse #2, the draw goes down to 0.06A
When unplugging Fuse #41, the draw goes down to 0.35A

Both of those are related to the instrument cluster according to the owner's manual.

What do I do from here? Any ideas/suggestions?

Thanks

 

You have to give the computers time to shut down, as well as the battery saver relay so your door and hood lights are out. Otherwise you're going to get a high reading.

When I'm testing for draw, I hook a jumper wire between the negative cable of one battery and it's battery post. Then unhook the other negative cable. Wait about an hour for all the computers to get shut down and for the hood and dome lights to go out. Connect your DVOM and then remove the jumper.

If for any reason you completely disconnect power, when you reconnect it all the computers will come up live and the dome and hood lights will come back on and you'll have to start over.

 

Thanks for the feedback! I tried it again.

Unplugged the light in the engine compartment and waited way longer.
It finally got down to 60mA, so I guess that's not my issue. :S

 

7 months later, my set of batteries is dead.


I still have this problem, I turn off everything, let the truck stand there till everything falls asleep with an ampmeter in serie with my battery setup.

I have a draw of about 0.4 amps till I pull the Fuse #2.
Fuse #35 and 41 don't change much.

Fuse #2 is the cluster, I decided to take it out and have a look.
Is this duct tape from the factory?



Thanks

 

Ok, so yes the duct tape is from the factory...

And after 45 minutes or so the current goes down to 0.05A...



However, I was measuring this at the driver side with the passenger side battery unplugged on the negative.

When I plug the passenger side battery in, I get a draw of 0.2A, 4x more! :S
(With the amp meter still on the drive side battery)



I've done another test, woken up the truck, plugged in the lamp on the hood...
I get a reading of 0.28A with two batteries plugged in and 0.88A with only one battery plugged in. :S
If the two batteries are parallel shouldn't the current just be double with 1 battery?

Any ideas on what I should test first at this point?

 

Un-hook the alternator cables and see what you get.
There is a plug and a cable. Also if the battery's
are not at the same state one will draw from the
other. This is why you replace them as a pair and
not one at a time.

Sean