Quick question - if I disconnect the car battery for a long period of time, will I have to reprogram the keys, TPMS(tire pressure sensors), etc.? In another word - will the ECU lose the car key transponder and TPMS data?

I have a LS460 2007 that is not driven frequently enough to keep the battery charged. I was thinking of installing a battery disconnect switch to prevent the battery from being drained. But worry about the remote keys and TPMS. Does anyone have experience in disconnecting the battery for a long period of time? Thank you!

 

The general advice I've seen here is to use a battery maintainer and keep it hooked to car. No damage will occur. There are times when disconnecting the battery for a half hour helps to reset certain issues. If you do as you are thinking, it may take a while to get everything working again. The multiple computers are designed to be on all the time. Then you'll be here again asking how to fix it.

 

TPMS won't erase (but sensors can drain their batts regardless), keys shouldn't too.
Radio settings, sound setting and nav setting will reset.

 

And yea, swfla is right, disconnected battery may die even sooner without cycling (car batts are made to be cycled). Connecting a battery tender/charger every, say, 3 month sould be sufficient to keep it alive and make sure batt is cycled.

 

Thank you Boykie! I was wondering why there are so many people using the battery disconnect switch. For example:
There are many YouTube videos talking about how to install/use these switches. And there are so many stores selling them. If disconnecting the battery kills it sooner, why people are still doing it? Thank you!

 

They might be doing it for security reasons. That's a pretty cheap looking device. This is a proper disconnect switch

 

People love knickknacks... And 200A doesn't even make sense with 600+A CCA rating of our batts. This is a trinket for some demo derby chevy or something.

 

Just use a tender system, get 3-10amps so that everything can be fed and still have headroom for the battery to be maintained

 

Get a CTEK trickle charger, worth every cent. You can leave it hooked up permanently and it won't damage your battery, just keep it topped up.

 

Had the best luck with the battery tender 1.25 amps

 

IDK all it'll have to relearn upon reconnecting the battery - but I knowwhen you disconnect the battery for anything, there are certain codes, that are different from OBD II codes, and that pertain exclusively to the smog system in the car. These are called "Permanent Diagnostic Trouble Codes" and unlike simple OBD II/"Check engine" light reset, these PDTC's do not reset automatically when you reconnect the battery.

A quick explanation of these "PERMANENT" codes
https://maspencef.blogspot.com/2021/...anent-dtc.html

and here:
https://www.bar.ca.gov/industry/pdtc

The PDTC codes are normally no big deal, since they eventually all reset themselves in the course of just driving the car normally. But how far you must drive to reset them, varies on every car - I had a 1999 Mercedes that took 500 miles to reset them all.

The only way to clear a PDTC is to fix the underlying problem with the vehicle (If any) that originally caused the PDTC...to set, and then allow the vehicle sufficient drive time to re-run the monitor that identified the problem in the first place. When the monitor runs without identifying a problem, the PDTC will clear itself.

Every time you disconnect the battery these codes are reset - but unfortunately the only way to get the PTDC codes back to how they were, is by driving the car. So just driving the car gradually resets the codes. BUT there is no shortcut to do this, nor can you do it with any kind of scanner or OBD II tool - only by driving the car.
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Normally just driving the car resets the PTDC codes in a few miles, and there's usually no need to even think about them because the computer takes care of it all on its own. BUT suppose you had to disconnect your battery and reconnect it for some reason, but now it's smog check time - and those codes are still reading a malfunction on the scan tool all because you haven't driven the car quite far enough for the computer to reset.
Now along comes the smog tech, and the first thing he does (in my state Calif anyway) is he hooks up his machine to your OBD II port and checks those codes for their values (the ""Permanent Diagnostic Trouble Codes" if any, will show on his scanner too). And if those codes are not reading what they are supposed to be, the tech is required to stop the smog test then and there, and he isn't allowed to proceed further until those codes are reset.
(Although a lot of states will allow one or two of the "PDTC" to be wrong and still will smog the car. For instance in California, you are allowed to have ONE of the codes to be wrong.)

So obviously it's easier not to lose those damn PDTC codes in the first place, at least not on purpose. But one way to avoid all this hassle, is to use a "memory saver" device. It is a simple contraption, powered by a 9v battery that plugs into the OBD II port. It's purpose is to store your car's settings while the battery is disconnected. So if you need to disconnect the battery, you can avoid losing all those settings just by using a memory saver.

If I were you I'd keep my car on a trickle charger. Unplugging a charger is no trouble at all... compared to having to go back and forth to the test station to pass smog.

 

I doubt they are using these switches on modern computer centric cars. Especially LS460. Lawnmowers, snowblowers, boats, race cars , campers, sure.

 

Marc you are confusing 2 different things. OBDII Monitors and Permanent codes. Monitors are the self tests within the ECU that need to be "Completed" after a battery disconnect (or code clear). THose are done by driving according to the "Drive Cycle".

Permanent codes are only present when there is a problem that trips a diagnostic trouble code. After repairing the item that tripped code the permanent code will stay around a while to verify the repair was made correctly. But that does not have anything to do with the mere act of disconnecting the battery.

 

I just use battery tender to avoid asking these questions.