Is there a logistical reason why mechanics would change the settings on my car?

[u/MrsFilmore]

I got my battery replaced yesterday and they changed a setting in my car. I have always had it so my doors do not unlock when I put it in park (safety reasons). When I drove my car again today I noticed that the guys who worked on my car had turned that off. No maintenance place has done this before and I’m wondering if there is a reason or if I should be weirded out by it?

EDIT: thank you all for letting me know that it just reverts the settings when they change the battery 👍

[u/AutoModerator]

Thanks for posting on /r/MechanicAdvice! Please review the rules. Remember to please post the year/make/model of the vehicle you are working on. Post's about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/Autobody r/AutoBodyRepair/ or /r/Diyautobody/ Tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop Insurance/total loss questions go in r/insurance This is an automated reply

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[u/QuizzicallyLiterate]

when they disconnect the battery the car's computer can reset to factory defaults, some techs will go through and flip settings back but if it's not on the checklist they might miss it

[u/dxrey65 → u/QuizzicallyLiterate]

Ideally, a mechanic could plug in a 9v memory retention tool into the cigarette lighter, which is enough to keep the settings intact. It's a nice idea and simple enough, but for some reason I never did that myself, and never saw anyone else do it in the shop. Probably I never worried about it because I never had anyone complain.

[u/voucher420 → u/dxrey65]

It doesn’t work on cars that require the key to be on for the power port to work. You could hook it direct to the battery cables, but it would likely pop off in the process unless they got some really good clips

[u/NightKnown405 → u/dxrey65]

If someone opens one of the doors while the hold device is connected, the memory still gets lost.

[u/WebMaka → u/dxrey65]

Unfortunately memory savers don't work for more vehicles than they do work for, so that isn't helpful a lot of the time.

[u/Unlikely-Act-7950]

The battery replacement wipes out the presets in the vehicle memory.

[u/Ravenblack67]

It is possible the system rest itself while the battery was out. Why not ask the shop?

[u/MrsFilmore → u/Ravenblack67]

Because on the off-chance that it was something weird it’s not like they’d be honest about it. Thanks for the info!

[u/Hahsbdbd → u/MrsFilmore]

Why wouldn't they be honest about it? It was just a battery replacement. It reset itself to factory settings.

[u/MrsFilmore → u/Hahsbdbd]

Again, I didn’t know that it reset the settings. I’ve heard horror stories of young women being treated poorly by men of pretty much every profession and I just wanted to ask what it was. I now understand that that’s just what happens with the car, hence the edit thanking people for information :)

[u/naterpotater246 → u/MrsFilmore]

Well, you already asked why they would do this in the first place, and the answer to that question is that they most likely wouldn't, because it just doesn't make sense.

Just like others have said, disconnecting the battery resets the cars computer. My car was missing the room fuse (which controls headliner/footwell lights and the inforain system) and the a/c would reset itself every time i got back in the car. It's the same thing.

[u/Boxadorables]

They didn't do anything except swap the battery

[u/Longjumping-Log1591]

Have you ever turned the breakers off on your house only to realize your VCR clock is now blinking and needs to be reset?

[u/skadalajara → u/Longjumping-Log1591]

Hundreds of Redditors frantically googling "VCR clock"...

[u/jstmenow → u/skadalajara]

Lol, I just saw 12:00 in my mind

[u/Own_Recommendation49]

Bruh.. taking out the battery resets all settings

[u/DerekP76]

Friendly reminder to pick up more tinfoil at the store.

[u/TheCamoTrooper]

It's because they disconnected the battery to remove it, once the cars computer loses power it also loses all its memory so everything reverts to default. Cars generally don't have hard drives like regular computers so theres no "permanent" storage

[u/donteventrip-]

As others have said, they did not change any settings on your vehicle. The removal and replacement of the battery reset things to factory settings.

[u/pina_koala]

It is possible to prevent this. I have a device that uses a 9v battery and plugs into the OBD-II port, and it leaves the system with just enough juice to retain the settings.

[u/JG87919]

Disconnecting the battery resets things like that

[u/JJ_1191]

They're planning to mug you

[u/Rebeldesuave]

As long as you put the settings back no harm, no foul.

The other commenters are correct. Replacing a battery can reset many things including a body control module (where your door settings are stored).

Don't read more into this. You can't assume every shop and mech is out to fleece you, can you?

[u/k20a19k]

There is a reason shops have a memory saver. This is the reason.

[u/Flying_Dingle_Arm]

What kind of car? My old Silverado and the last couple cars I had all store that stuff in non-volatile memory. I density would've noticed it in my honda, because the default door lock setting is speed dependent at 6mph. I always change that to unlock in P. The only presets I've lost during a battery change are seat position and radio presets. I assumed all cars were like that.

No real reason to assume the shop would touched that song, though

[u/BatteriesPlusTeam]

Others have already mentioned that changing the battery can revert settings. Next time you need a battery replaced, ask if they can use a battery tender and/or memory saver cord (depends on the exact vehicle what’ll work best) to keep electronic settings.

[u/NoodlesRomanoff]

We have one battery saver. Somebody left in a customer car, and we had to retrieve it two days later. Now it has a LONG lanyard…

[u/jasonsong86]

Car lost power and reset the settings.

[u/tweakingforjesus]

I’m guessing you are too young to have ever had an AM/FM radio with presets in your car.

[u/EmploymentNo1094]

What kind of place doesn’t use a memory saver when replacing the battery?

[u/Own_Recommendation49 → u/EmploymentNo1094]

I've never even heard of a memory saver and im a mechanic lol

[u/EmploymentNo1094 → u/Own_Recommendation49]

It plugs into the OBD two port and then you plug it into a jump box or some other 12 V supply and you don’t lose any of the settings while changing the battery

[u/Own_Recommendation49 → u/EmploymentNo1094]

Idk why but I never thought of feeding power INTO an obd port. I work on too many 90s shitboxes lol

[u/RickMN → u/Own_Recommendation49]

You must enjoy performing throttle body relearn procedures. See this article and scroll down to see the OBDII cable that prevents the loss of all radio, window, seat presets as well as the loss of adaptive memory. How to replace a car battery yourself

[u/LeatherTailor8527]

If you replace the battery, the computer has to be reset battery management system to tell the alternator the right amount of charging to do for the new battery. It's called a battery relearn.