Battery replacement and the 'puter

I gotta new to me 2017 4R. I watched a You Toober explain that when it's time to get a new battery, the computer will lose power and all its programming when the battery is disconnected. They recommended using a portable battery charging device with a "cigarette" plug inserted in the correct power port in order to change the bat w/out the 'puter losing power. Really? I never heard of this. I never had a problem with the computer after changing bat's in other cars. Whadda ya think?

 

Welcome to the forum.
this is what you are referencing..https://www.nationaltoolwarehouse.c...2ll6BAsBXQMXgCItV-iesjxGlA2V6I64aArPwEALw_wcB

Will save time if you replace a lot of batteries and do not want to write down and program pre sets/seat settings etc. On your own rig it isn't needed unless a personal preference to save time. Basically if you do not have it, You can replace without it.

 

The ECU won't lose its memory unless the battery is disconnected for awhile.

As far as other settings, radio presets, etc, maybe check the link posted by @RumHamRunner73 .

 

I don't bother personally.

 

Not sure what people are referring to when they say "ECM losing memory". Yes, the readiness monitors will need to be reset, but normal driving will do this for you. Maybe google readiness monitors after battery disconnect. I'm pretty sure that's what is being referenced.

Additionally, you will have to reset your clock and radio stations like you always have.


Personally, I use a memory saver because its faster than resetting the clock and radio stations.


Also note that some new cars need to have a battery reset procedure done when replacing the battery. These are usually ECM controlled charging systems. The ECM adjusts output based on older a battery gets. If the ECM does not know there is a new battery installed, it may overcharge, which could shorten the life of the new battery.

 

The ECU makes little adjustments over time. If it loses power long enough, it reverts to factory settings. It's generally not really a problem, though.

 

Is this just with the newer stuff? I've never had an issue but I've only worked on "old" stuff. When I bought my '19 the battery crapped out about a week later. I didn't really even think about it and just plopped in a new one and went on my way. My wife's '05 usually loses the auto up/down on the windows until I run each one all the way down and up individually, but we never lose radio stations. No seat pre-sets so there you go, less is more.

 

Any vehicle with an ECU that "learns" can lose its memory. But, it's almost never going to actually cause a problem.

For example: When I replaced the timing belt on my 2003 4Runner in 2016 or 2017, it would not idle afterward. Through some Googling, I learned that the throttle body was probably filled with carbon buildup, which the ECU had been compensating for. Once the ECU reverted to factory settings, it no longer made the adjustment and would not idle. I took the intake off, cleaned up the throttle body, and then it ran fine.

 

I need to find where to get that patch....

 

Couldn't you just use some jumper cables and hook up another battery in parallel while you replace the old battery? And not lose any settings.

 

Thanks to all. I think I will prolly just "throw the dice" and swap out the battery likity split when the time comes.

 

Some vehicles are more finicky with battery changes, requiring module relearns with a scan tool, etc. The 4R is simpler so fewer things are needed. Your engine will likely stumble and shut off on the first startup after battery replacement. That is from throttle body relearn. Subsequent engine starts should be normal. You will need to set the clock and compass zone again.

Don't be rushed with battery replacement. Take the time to remove the plastic catch tray and clean up any corrosion in the fender from spilled acid. Clean the cable terminals with a wire brush.