guardrail22

Btw. Mine is a 2012 Lariat that was built Aug 2012 and I bought it end of March 2013. New battery a month ago.

Va-Rob

Yes, I have the factory installed trailer brake controller.

guardrail22

something in common. Have you plugged a trailer into the truck yet?

Va-Rob

No, I have never plugged in anything to it. have you had any issues since the new battery? kind of hard to test it without using the truck.

guardrail22

This battery dies the same way the original did. Ford is requesting dealer check connectors for water intrusion but I dont think thats it. The TBC circuit is hot all the time and its either drawing thru a partial ground or a part that isnt deenergizing.

KnuckleBuster

I know it's an old thread, but it happened to me twice in the past month on a brand new 5.0 truck with less than 2K miles. The dealership claims there is no parasitic loss and the battery is fine. Won't even replace the battery. The battery holds a full charge for a while and then just dies out of the blue overnight. Find a good aftermarket battery and if it happens again, there is parasitic loss somewhere.

guardrail22

What has the dealer done to convince you they know how to find a draw when everything is shut down

KnuckleBuster

BTW, I checked for parasitic loss the old fashioned way with a multi-meter, checking the amperage for each circuit in series off the terminal. Pulled every fuse. A technician advised me that it was pretty much useless to do so on these trucks, because they take 40 minutes to go into sleep mode, there are multiple computers, and they wake up each time a fuse is pulled. The sad reality is, unless a code is thrown to a scanner at a dealership, the first step to the R&R method is to replace the battery to at least eliminate that possibility, then confirm it is a stuck relay or something elsewhere in the truck.
...That being said, I did detect steady parasitic loss, but the tech advised me the truck was probably awake.

stormsearch

That tech is wrong.

All '09+ trucks are asleep within 15 minutes. If the modules keep waking each other up, then there is an issue with Module/CAN communication. Also, you won't wake up the system when pulling a fuse unless you open the door to do so. You basically need to stay in the truck and read the meter while pulling fuses.

An awake truck will easily pull 500mA or more. Most modules won't pull that much during a parasitic drain (IP cluster and Radio Head Unit are some of the exceptions).

But he is correct on changing the battery. Time is money, it is just faster to replace the battery. Dealerships sell off the used batteries so really they don't lose much money. Hope is next time truck is out of warranty, or driving habits change to keep a higher state of charge or get lucky and the battery was faulty to begin with (which really isn't out of the question with today's batteries).

guardrail22

Great info except when the battery isnt the problem. I have a new battery and truck kills it in 36 hours. I watchec it yesterday. Raised the hood and just checked it periodically. At 7v it wont even move the door locks or light up the dash and it supposedly has battery protection in it.