I did a search and found conflicting statments regarding removing both batteries or alowing both to fully discharge. I have one bad battery ( both are 14 months old ) and other seems ok but havn't load tested it so I want to carry it with me but 2 trips is possiable if that will save some hassel. Some have said if both batteries are disconnected,a process must be gone through after reinstallation to reset some electronics.

Take-um both off or take extra 10 minutes taking them in one at a time?
I guess I might also ask how long and hard should I insist both batteries be replaced under warranty if one tests good?

Thanks folks. Simple minded question but like so many,I have about decided that while being a great performer,a 6L can be like a tempermental wife you best walk softly around lest you pi$$ them off.

 

take them both the relearn is only 03-04 and will happen on its own.
you can try to fight the warranty good luck as it wont likly happen

 

I have had my batteries disconnected for hours and didn't have a problem and any relearning the PCM has to do can be done with normal driving, like the transmission might shift a little funny until it goes through its relearning cycle. That being said the batteries should be replaced in pairs as the one that is still good may not be good for long as it has undergone the same stresses as the one that failed.

 

Man Cheezit, you beat me to it, I need to learn to type faster

 

Thank you fiends. And 40 lashes to me for not having my truck show in my posts ater over 3 years. I will tend to that right away.
2004 F-250 Crew 4x4 auto 6.0PS

 

The relearn is 2003 and newer. All TorqShift transmission controllers, both five speed and six speed, will learn parameters to make them shift better. It was not limited to the 03-04 trucks.

 

ok mark ill let you have that, i know its the correct awnser...
i was thinkingg the turbo relearn

 

Don't flame me guys, but I have Kirkland batteries that I bought at Costco. They're actually doing pretty good, except one of them took the dive last Summer while on the road about 500 miles from home... The point here is, I went to a Costco down there and took both batteries in for warranty replacement. They replaced both batteries, even though one tested good. I told them it was a diesel and that you don't replace only one battery with a diesel. No questions, two new batteries.

 

Good things happen - sometimes.

I've had parts replaced free once - and they wrote on the receipt "already replaced" and told me they won't re-replace the part again.
Hopefully your new batteries won't go down that road.

Nothing (except our 6L and trucks) seems to last any more.

 

I just had this same experience with costco. I don't have any idea on the quality of their batteries, but the Excursion I purchased already had Kirkland signature batteries in it. I decided to replace them, do to my FICM issue, and they didn't even bat an eye. One battery was leaking, but both got replaced for free under their 36 month warranty. No questions asked, just a "sorry for you trouble, sir".

 

Yup, me three. Just replaced 2 batteries for trailer, put them in the cart, she wrote me up, I went and picked two new ones. No fuss no muss. I have motorcrafts right now, but thinking serious about Costco next time, should be in another three years for the truck.

I say disconnect both batteries, don't be afraid of the relearn!