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Which fuse to pull to reset ECU w/out having to pull neg bat cable?


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Hey All,

 

Just wondering if anybody knows which fuse you need to pull (if any) to reset the ECU. Id rather do it that way as I dont want to reprogram my stations and clock every time I may want to reset the ECU.

 

I just hit 1000 miles today and want to reset the ECU so it forgets all the granny driving I did and learns what its real life is going to be like!!!

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I don't think you can do that. You still have to disconnect the (-). But you may make a trip to your local Murry's Auto or Autozone and buy some cables and a switch and you may set up a 'battery disconnect' switch yourself. Image...in the unfortunate event of electrical fire...you can just pop the hood open, flip the switch and eliminate some of the dangers :-) Honestly...I think all cars should have such a solution, just as they have a switch (impact) for the fuel tank, there should be one (manual) for the battery.
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Highly improbable for an electrical fire and if one did flare up, popping the hood to flip a switch would be the last thing I would want to do. Imagine the surprise the subaru investigators would get when then find the remains of your cables and switches. Lord help us.
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Hey All,

 

Just wondering if anybody knows which fuse you need to pull (if any) to reset the ECU. Id rather do it that way as I dont want to reprogram my stations and clock every time I may want to reset the ECU.

 

I just hit 1000 miles today and want to reset the ECU so it forgets all the granny driving I did and learns what its real life is going to be like!!!

 

why not jsut leave it and let it learn your new driving habits normaly. it wont take any time more or less then doing what u want

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With past cars, the ECU is slow to learn habits, good or bad. Just like with any "performance" mod, an ECU reset is suggested to allow the car to take full advantage of whatever part you just installed. I figure the new way I will be driving is a pretty big performance mod in its own right, and would rather speed things along than wait the X amount of drive cycles or miles before it starts behaving like I think it should.

 

My last car had a ECU fuse or (PCM Fuse) whatever you want to call it that protected it from whatever a fuse protects electrical components from. To reset the ECU, all you had to do was pull the fuse for a good 5 mins or so and all was reset. And you still had your clock and stations still happily programmed. All the good w/o the bad.

 

Ill have to pull the manual out tomorrow and check for myself. Im guessing every car has a fuse for the ECU/PCM, I was just wondering if anybody knew off hand.

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I think I found it. Looks like Fuse 12 in the interior fuse panel. Listed as Engine Control Unit (and other things). I believe this should do the trick.

 

I pulled it for about 5 minutes and put it back in. Tomorrow I will see if I notice any difference in the cars behavior. I may or I may not, but its worth a shot.

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nah, the best way to purge all memory is by undoing the neg off the battery, push on the brakes to discharge the entire car, then put the neg back on to battery. It's also known as the "dyno-purge" to do it this way for reflashing or any other electrical mod.

 

Keefe

Keefe
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nah, the best way to purge all memory is by undoing the neg off the battery, push on the brakes to discharge the entire car, then put the neg back on to battery. It's also known as the "dyno-purge" to do it this way for reflashing or any other electrical mod.

 

Keefe

 

in additon to this

i take the neg cable and ground it to the positive end. letting any avilible power back feed and drain the capicitors and what not

then i step on the brakes

turn the key on

flip the headlights on

jsut press all sorts of buttons to drain the capacitors

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the ecu should be the only thing that holds any sort of data or settings. pulling the battery cable or pulling the ECU fuse should have exactly the same result, an ECU that is set back to its factory defaulted settings.

 

the only way i could see a difference between the 2 methods is if there was another computer controlling say shiftpoints in an AT tranny, and resetting one may not give you the true base settings.

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in additon to this

i take the neg cable and ground it to the positive end. letting any avilible power back feed and drain the capicitors and what not

then i step on the brakes

turn the key on

flip the headlights on

jsut press all sorts of buttons to drain the capacitors

 

Just disconnect the negative terminal on the battery and step on the brakes, put the keys in the ignition and flip it to the 2nd position (ON) to ensure NOTHING on the instrument cluster is on. I dont think you have go through ALL stated above.

 

Keefe

Keefe
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Just disconnect the negative terminal on the battery and step on the brakes, put the keys in the ignition and flip it to the 2nd position (ON) to ensure NOTHING on the instrument cluster is on. I dont think you have go through ALL stated above.

 

Keefe

 

yeah but i like to over do it and add extra steps! jsut agree with me

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The correct way to reset the ECU is to connect the 2 green connectors under the dash in the Passenger's side fottwell and turn the ignotion key to ON. At that point the ECU will be reset. Turn the Ignition key off and disconnect the 2 connectors.

 

There is also an identical set of connectors under the dash on the Drivers side but they are a little harder to get to.

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  • 15 years later...
Hi everyone. I am a new owner of an 05 Legacy sedan 2.5 limited. The other day, I swapped my seats for some coming from an 06 Legacy GT with power seat on passenger side. Mine already have power on the driver side, although, that’s where the problem starts. I made the mistake not to disconnect the negative cable from the battery so when I was trying to fit the passenger seat by plugging the wires, I heard a spark coming from under the dashboard. Since then, I no longer have door locks, no ceiling light, no rear window defogger, no mileage display in the dashboard. My shifter doesn’t shift from park, unless manually. Yes I verified and re-verified the fuses one by one, but no lucks whatsoever. As you probably guessed, it’s an Automatic. Any advice will be greatly appreciated as I am very tired not knowing what to do. Also, my chime goes off every 10 seconds, but I know this is due to the swap of the seats. Thank you all in advance. Al from Canada
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