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Discussion Starter #1
I hope I'm using the proper terminology. I'm thinking about replacing the head unit in my '06 Forester. All the instructions I've read tell you do disconnect the battery before you start. But I seem to remember people mentioning that disconnecting the battery was a way to "reset the ECU" or some such thing so that the automatic transmission could re-learn optimum shifting points. My car is running and shifting quite smoothly, thank you, and I'm hesitant to mess around and screw that up.

Am I "misremembering" something or is there some way to get around the reset and still disconnect the battery if I install an aftermarket HU?

Thanks.

P.S. I'm still looking if anyone has a stock CD changer from an '07 or '08 Forester that they're interested in selling.
 

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2014 2.0XT CVT
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The only reason they tell you that is for safety. Any time you work with electricity it's a good idea for you and the parts you're working with to disconnect the source. In all my experience installing well over 100 head units in the last 10+ years, I have never disconnected the battery to install one. that being said you are working at your own risk if you don't disconnect but I've never done so and have never had a problem.
 

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2007 Forester Sports XT 4EAT
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I hope I'm using the proper terminology. I'm thinking about replacing the head unit in my '06 Forester. All the instructions I've read tell you do disconnect the battery before you start. But I seem to remember people mentioning that disconnecting the battery was a way to "reset the ECU" or some such thing so that the automatic transmission could re-learn optimum shifting points. My car is running and shifting quite smoothly, thank you, and I'm hesitant to mess around and screw that up.

Am I "misremembering" something or is there some way to get around the reset and still disconnect the battery if I install an aftermarket HU?

Thanks.

P.S. I'm still looking if anyone has a stock CD changer from an '07 or '08 Forester that they're interested in selling.
Unless you have "other" existing problems with your vehicle, disconnecting the battery on your year Forester will cause no problems. One thing that will make starting easier after the battery is reconnected, is to turn the ignition key to start, but don't crank. Wait 15-30 seconds, then start. This gives the ECM time to sync up & your engine will start normally. If you don't do this, the first start may take longer (cranking), than usual. :wink:

Bottom line. It's always a good idea to disconnect the battery when working with electrical stuff. As careful as I am, I've had some sparks. :icon_eek:

BTW, my experience tells me that you'd be much happier with an aftermarket head unit. The low end ones are very inexpensive & will still out perform a factory/OEM head unit. :smile:

Bobby...
 

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Discussion Starter #4
Thanks, folks.

As I look again at the instructions, it mentions only disconnecting the negative terminal. Maybe that's enough to prevent any issues with electrocution and messing up any memory in the car's computer. Or maybe not. :icon_wink:
 

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the funny thing is if you look at just about every install instruction that involves something electric it will say disconnect the negative battery. The best thing (and I wish I had a picture) was the manual for the 99 Mercury Cougar (only had one to build an electric car in college) had the instructions Step 1: Disconnect negative battery terminal, Step 2: open the hood.

I may never forget that one
 

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2007 Forester Sports XT 4EAT
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Thanks, folks.

As I look again at the instructions, it mentions only disconnecting the negative terminal. Maybe that's enough to prevent any issues with electrocution and messing up any memory in the car's computer. Or maybe not. :icon_wink:
You won't get electrocuted with 12V, burned, perhaps. :icon_eek:

When you look at the battery, you'll see the negative side is connected to the frame of the vehicle. The metal of the vehicle is used to save on wiring. That means when you lift off the negative battery lead, it's like turning off the main power switch. :wink:

Bobby...
 

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2017 2.0 FXT-Touring CVT
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the funny thing is if you look at just about every install instruction that involves something electric it will say disconnect the negative battery. The best thing (and I wish I had a picture) was the manual for the 99 Mercury Cougar (only had one to build an electric car in college) had the instructions Step 1: Disconnect negative battery terminal, Step 2: open the hood.

I may never forget that one

I love ford.

No I don't.. not even a little.
 

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It will reset the ecu, but within a short amount of time the ECU will relearn and run everything exactly the same as it was before. It basically resets to granny driving mode and will learn based on the way you drive but this happens relatively quickly. I reset my ecu regularly just due to the wide variation in the quality of gas around here.
 

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2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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By not disconnecting the battery, the MOST you'll ever do is shock yourself (has never happened to me, ever), or possibly blow a fuse (which I've only done once). That's it. 12v is easy to work with. In fact, just about every head-unit I've installed (dozens over the years), I've never disconnected the battery, unless I was installing an amp, then you kind of have to.

Just wire up your harness to the head-units' harness (you don't do this with it plugged in, so there's no way you can zap anything). Then when you're done with that, you just plug it into the cars harness and you're done. You would REALLY have to be trying to mess up on purpose to shock yourself or blow a fuse.
 

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Discussion Starter #10
Great info. Thanks, everyone.

I'm finally getting over my fear of having an aftermarket unit stolen (even though it will be a cheap one), and I'm now leaning in that direction. Plus, as I'm discovering, I can get a lot more for my dollar with an aftermarket unit. I was looking for a stock unit just to maintain the stock look and to deter thieves, but it's not that easy to find a stock unit worth having that will be an simple swap out.
 

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Why not just pull the fuse for the radio so you don't have to disconnect the battery if you are concerned about the ECU loosing its settings.
 

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Great info. Thanks, everyone.

I'm finally getting over my fear of having an aftermarket unit stolen (even though it will be a cheap one), and I'm now leaning in that direction. Plus, as I'm discovering, I can get a lot more for my dollar with an aftermarket unit. I was looking for a stock unit just to maintain the stock look and to deter thieves, but it's not that easy to find a stock unit worth having that will be an simple swap out.
The head unit upgrade is very easy to do. I just posted my head unit upgrade here today. :wink:

Bobby...
 

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Discussion Starter #13
Nice pics. I was all set to ask if you wanted to sell that '07 head unit, but I see someone beat me to it. :icon_wink:
 
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