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Will removing my battery connectors reset my ECU?

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I was going to clean my battery & cables with NOCO and NCP2 spray to insure it doesn't have any corrosion since I have a slow battery drain. A guy at a shop told me some vehicle models run pretty bad when you disconnect the negative terminal because it resets the throttle, ECU and modules.

I plan on cleaning my 2002 Jeep Grand Cherokee Laredo 4.7L (VIN-N)
My dad's 2005 Dodge Dakota SLT
My Mom's 2003 Ford Taurus 4 door station wagon.

Will I run into any problems?
Will I have to enter codes or will they be old enough to not worry?

Do I need this memory/ECM saver?

VSTM OBD II Vehicle ECU Emergency Power Supply Cable Memory Saver (3Meter) with Alligator Clip-On 12V Car Battery Cigarette Lighter Power Extension Socket https://a.co/d/evXYlzr
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i have never had that issue. things like clocks and stereo will need resetting up. But that is my experience take it or leave it.

back feeding the system through the OBD2 sound more risky to me. more so from something made in china for 14 bucks. that claims works on all.

I have heard on these latest jeeps it can be an issue, but no personal.

the 12 JKR i have has had that battery out many times. not an issue with it. None of the last vehicles owned in my 45 years of driving have as well.
 

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It's convenient to use a memory saver so your clocks, radio etc don't go back to default. The ECU will default back to a stand 'ready to run' state and tuning will return with use, but it's better to keep all the settings
 

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Discussion Starter · #4 ·
It's convenient to use a memory saver so your clocks, radio etc don't go back to default. The ECU will default back to a stand 'ready to run' state and tuning will return with use, but it's better to keep all the settings
So will my 02 WJ run poorly, and if so how long does it take to reset ECU settings? How fast do I need to drive and for how long?
Or is there a dumb complicated way to fix it?
I was hoping a 20 year old Jeep should be safe to remove battery without having to reprogram at shop.
I changed my battery a while back and think I remember a rough start and odd idle. Maybe the TB/IAC/MAP was reseting its parameters.
Just wondering if there is a proper way/method to get it back to optimal
 

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Discussion Starter · #5 ·
i have never had that issue. things like clocks and stereo will need resetting up. But that is my experience take it or leave it.

back feeding the system through the OBD2 sound more risky to me. more so from something made in china for 14 bucks. that claims works on all.

I have heard on these latest jeeps it can be an issue, but no personal.

the 12 JKR i have has had that battery out many times. not an issue with it. None of the last vehicles owned in my 45 years of driving have as well.
That does make me feel better, you think it's the same with my parents 03 Ford/05 Dodge?
i have never had that issue. things like clocks and stereo will need resetting up. But that is my experience take it or leave it.

back feeding the system through the OBD2 sound more risky to me. more so from something made in china for 14 bucks. that claims works on all.

I have heard on these latest jeeps it can be an issue, but no personal.

the 12 JKR i have has had that battery out many times. not an issue with it. None of the last vehicles owned in my 45 years of driving have as well.
That does make me feel better, do you think that it will be safe for the 2005 Dodge Dakota SLT and 2003 Ford Tuarus Wagon?
 

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Make up a lead a couple of feet long
with a small ring connector at each end.

Drill a small hole in top of the battery posts.
Drill a small hole in each battery clamp.

Using small screws,
screw one end of you lead
to one battery post.
Screw the other end of the lead
to that post's clamp.

You can now remove the clamp
without losing memory.

Tape the clamps with gaffer tape
to insulated them
as soon as you take off
otherwise sparks will fly.

I do something similar
when I chase excessive
ignition off draw.
I have an ammeter between
1 post and a clamp.
 

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So will my 02 WJ run poorly, and if so how long does it take to reset ECU settings? How fast do I need to drive and for how long?
Or is there a dumb complicated way to fix it?
I was hoping a 20 year old Jeep should be safe to remove battery without having to reprogram at shop.
I changed my battery a while back and think I remember a rough start and odd idle. Maybe the TB/IAC/MAP was reseting its parameters.
Just wondering if there is a proper way/method to get it back to optimal
I would NOT say it would run poorly, it will go to factory default which is intentionally fairly stable, you might not even notice it, but I wouldn't do it just before inspection
 

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Chit man. I disconnected my negative battery cable many times to try and get rid of codes until I bought a code reader. I just needed to reset the presets on the radio. It started and ran fine afterwards. Batteries go dead all the time in all kinds of vehicles. You also have to totally disconnect a old battery to put in a new one. Just do what you need to do and quit worrying.
 

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I recently had the check engine light come on in my 01 WJ 4.0. Code P0456-evaporative emissions control. Happens almost every year when the temps drop. The fuel cap most likely culprit as the hoses look fine. The light went off after a few days of driving and because I had inspection to go through, I disconnected the negative cable for a good 15 minutes. The code was gone, and the only thing that happened was my miles were reset and the display up top shows 0.0 mpg. It ran fine and I replaced the O-ring on the fuel cap. The Jeep went through inspection no issue. Here in N.J. that is an accomplishment. They only check the fuel cap, paperwork, and emissions.
 

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...The Jeep went through inspection no issue. Here in N.J. that is an accomplishment. They only check the fuel cap, paperwork, and emissions.
Funny story: I checked the ZJ with my HF scanner before going and everything OK. Scanner at inspection refused to connect. Took it to a mechanic friend, his SnapOn said 'OK". Took it to another 'official emissions shop' and his shop scanner said ok, but the state scanner would not connect.

Eventually a friend of the mechanic ID'd the problem. There are two grounds on the OBDII interface -- shop scanners normally tie them together for testing, but the state unit does not. Jumpering the second ground fixed everything.
 

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When u disconnect anything with an electronic throttle body you just simply need to start it and let it run until the electric fans have come on twice and the vehicle is at its operating temp. It's also good to clean out the throttle body since it has to go threw a re learn
 

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Discussion Starter · #14 ·
When u disconnect anything with an electronic throttle body you just simply need to start it and let it run until the electric fans have come on twice and the vehicle is at its operating temp. It's also good to clean out the throttle body since it has to go threw a re learn
Good to know, but funny story the thermostatic switch 🤣 is gonzo. The mechanic that set up the electric fan setup with thermostatic probe in place of the hydrolic fan system that comes stock kinda did **** Hella ghetto.
No relay, no fuse, only hardwire from battery to therm to fan.
I don't believe it works anymore and I'm gonna rewire a new one and use a laser thermometer to set the temp to 210°F and off on 195-200°F
I'll use a relay, a fuse between battery & relay and a new shiny therm probe next to top coolant hose in radiator fins.
But it's winter and I don't need it yet.
Jeep runs around 195-200°F and stays solid.
But now I gotta change oil + filter + PVC valve, get a new oil fill housing + baffle + gasket. Then I'm changing front Tie Rod Ends, LCAs and rear Sway Bar links, U/LCA's and possibly the upper control arm ball joint pre-assembled in tribolt bracket + A-Arm.
Should only cost me $400 for suspension parts.
The therm switch will cost around $60 with 10ga OFC silicone wire.

Pretty goof for a Jeep that cost less than $500. Love my Jeep and it has a hellishly robust engine.
 

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So will my 02 WJ run poorly, and if so how long does it take to reset ECU settings? How fast do I need to drive and for how long?
Or is there a dumb complicated way to fix it?
I was hoping a 20 year old Jeep should be safe to remove battery without having to reprogram at shop.
I changed my battery a while back and think I remember a rough start and odd idle. Maybe the TB/IAC/MAP was reseting its parameters.
Just wondering if there is a proper way/method to get it back to optimal
My 02 does not run poorly after removing battery cables. In my case, the difference is barely noticeable. Tranny shifts OK too.
 

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My 02 does not run poorly after removing battery cables. In my case, the difference is barely noticeable. Tranny shifts OK too.
Thats what should happen--only relatively small relearning should be necessary. Also if you have had any factory update patches, they should be unchanged by the disconnect.
 
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