Asking on behalf of my brother, what are the correct ways to reset ur car ecu manually ? I heard that u can do it by removing the battery terminal and then attach it back ? What are the correct ways to do it ? And also what are the benefits of doing it >?

no benefit indeed. Some says better fc after reset.

what car??

not all cars just plug in the ecu and roll out of the factory, most ecu has to be programed to a fuel/o2 balance mixture, auto transmission shifting, cam/valve timing, etc.

by removing battery only allow the ecu back to zero or "default", doesnt mean that the setting is same as the time when it roll out from the factory.

pro: cheap way to reset ecu if the program is messed up
con: most obvious issue is the auto transmission shifting timing problem & jerkiness

correct way: send your car back to service center for ecu reset, they will reload the program after resetting the ecu.

I would say depending to the car itself. Toyota's ECU will be able to relearn after being reset(or change battery outside)
While Wira VDO ECU can be reseted and not much problem after that.
Most ECU has a fail safe(or default) setting, it might not be the best, but still can work... Only FC slightly higher...

Still, cannot find a reson to deny your statements on send back your car for checking...

plug out the plug in negative terminal of the battery for 10-15mins then plug it back, your ECU should be reset by now

no real benefit of doing it, want good fc, control your right leg

my bro driving saga blm auto

i have a blm auto as well and reseting ecu did help but not much cause it learns your style of driving again,all depends on your right foot and try to keep speed limit between 90-100km/h.

If use the wrong method to reset the ECU, for sure it won't have effect.....
Right way to reset an ECU is, you must drained out all the charge stored in the ECU....

how to drained out all the charge ?

Unplug +ve first or remove the fuse for ECU only. Then wait for 5-10 minutes.....

My friend is driving saga blm auto too, his fuel consume is very bad. Around 6.6km/L Full city drive.
he went to SC ask for reset ECU but been refuse unless give they test drive 112km. (Kuching-Serian)
he looking for other solution. Are other shop provide service?
Anyway, Service book important? what happen if gone?
I ask he where the service book, He say the Salesman tell him gone liao. (he purchase 2nd hand saga)

hmmm, service book is important if you are buying second hand car since the only prove that the car has been serviced is on the service book itself wihout the book , its quite hard to prove that the car has been previously serviced according to schedule which is the first 1000km, 5000km , 10000 km and so on Anyway, i think he can manually reset the ECU himself by unplugging the +ve side of the battery for overnight then plug it back

for saga blm if go for manual i think maybe still can save fuel and better pickup, some of my friend drive auto they say all makan minyak one

For Proton, is good to get manual tranny, auto it won't yield good results.....

Who taught you to unplug the +ve terminal first ?

This post has been edited by Maapu: May 25 2011, 01:44 PM

Negative terminal la dailou zzz

Then who thought you to remove -ve terminal first? Just do your self this simple test, which method can send your HU's settings go back to default.....

Both would remove the settings and the correct way is to disconnect the -ve terminal first. Some HU installers, esp when you have an expensive sound system, they might ground your HU directly to the -ve terminal of the battery. So in your case, by just removing the -ve terminal, you have not removed the -ve terminal for your HU and therefore have not disconnected the electrical circuit. In any other cars with only 1 -ve grounding source on the battery terminal, all electrical equipment would reset with the removal of the -ve terminal.

The correct procedure to remove the -ve terminal is to prevent sparking/arcing/surging of power when you reconnect the terminal.

This post has been edited by sleepwalker: May 25 2011, 02:35 PM

for safety purposes always remove the -ve terminal first to 'kill' the battery. it has been practiced many-many years and everywhere. no reason not to follow it.

This post has been edited by soulfly: May 25 2011, 02:36 PM

That's a wrong practise.
What if the equipment still got charge and you accidently touch it? Your way still consider a safe way?
The proper way to deal with this is when want to remove, unplug +ve first then -ve. And when want to connect back, connect +ve then use a small wire to energize he equipment first before putting the main -ve back to battery.

most car (if not all) will have an ECU fuse... find that fuse, take it out and then connect it back after 1-2 minutes...

The moment you disconnect -ve, you disconnect the circuit and there will be no charge. You can't charge something unless you complete the circuit. That is why when you remove the -ve first, there is no sparking when you remove the +ve. The circuit is gone and you can take the +ve connector and touch the +ve terminal all you want. Fundamental Physics 101 (unless you want to argue with that too and change the laws of physics).

If you leave the -ve terminal connected and remove +ve, you'd get sparking because the circuit is still connected through all the equipment. For somebody with so much ICE in his car, you should know that there is nothing in the car that will hold any charge except for a capacitor.

But now we are talking about discharging, right? Or I get some info wrong here?
BTW, as what another member said above you, remove the fuse only can do to reset the ECU. Or you are trying to tell me that, the fuse is connected to the -ve?

a typical case of "I Reject Your Reality And Substitute My Own" - quoted adam savage

it is a fact that always remove the -ve terminal before +ve.
it is a fact that fuse always has to connected to the +ve terminal.

changing a car batt for dummies:
link

Do not quote people out of context. You tend to do that and you quote people wrong. 'Remove the fuse only can do to reset the ECU". Which part of his reply said that? He said that reseting the ECU can be done by removing the fuse to the ECU.

Here are some rules for noobs like you.

1. For most ECUs, disconnecting the electrical circuit will erase the RAM that holds the variables to 'learnt' settings.

2.The fuse is part of the electrical circuit and by removing the fuse, you are disconnecting the circuit. Therefore rule one has been achieved.

3. Removing either the +ve or -ve terminals will also disconnect the electrical circuit and hence rule one has been achieved.

4. However, the correct way to remove the electrical terminals from the battery is to remove the -ve terminal first. This rule has nothing to do with the disconnection of the electrical circuit. It just highlights the proper way to remove the terminals.

And before you say anything about the fuse being located between the +ve terminal and the ECU/electrical component, you have to go and ask your physics teacher why there are 20 plus small fuses in the car instead of one BIG fuse. Here's a hint and it has something to do with amps (amphere.. not amplifiers). That is why it is ok to remove fuses without risk of sparking, unlike removing the +ve terminal.

One more thing. The ECU does not hold charge. The ECU has both ROM and RAM. The factory settings are all stored in the ROM and is not removed when you disconnect your battery. The RAM, like computer RAM, needs electrical power to store memory. There is actually no need to leave the ECU for 15 mins. The moment power is disconnected, the RAM will lose all of its contents.

Some ECU has it's own backup battery that will keep the settings alive even when you disconnect the battery. Like my car, I have to plug in the notebook to reset the ECU. It does not work by removing the battery.

This post has been edited by sleepwalker: May 26 2011, 08:28 AM

Now I'm very confuse, is most = all?
And your rule no. 1 are having conflict with your last statement.
What a physics teacher have to do with engineer? It is 2 different job.
As long as the circuit are open(by removing the fuse), by the time you close the circuit by putting the fuse again, it will still create some sparks, you don't notice it does not means doesn't has. Just it is not enough ampere to create obvious sparks.
If you read the wiki link, why when we connecting back all the terminals, we have to put +ve first and not -ve first?

erm u do realise right anyone can edit information on wiki?


wiki cannot be the gospel truth...

maybe just as reference.. but you cannot take it as face value...

what we are all trying to teach here is that the proper way to disconnect a battery... example, which terminal should be disconnected first....
-ve first then only +ve...

btw most is not the same as all...

aduh !!!

^Infact I know that, just that people will blindly follow regardless it is a fact or it is a flaw.
And resetting my ECU, the fastest way still remove the +ve and crank it for once and it stop my rpm's bad fluctuation. Removing -ve result to nothing.....

That's because the amp would be low enough to put the fuse without too much risk of surging (you can't surge through that tiny wire), whereas the +ve terminal has to feed the amp to the entire car and the current surge is much bigger (notice the difference in the size of the -ve terminal cable with a normal equipment wire).

Electrons and electron flows belongs to the physics department. Not engineering. No wonder you got it all wrong. You've been learning from the wrong source. Physics is the law, engineering is the construct based on the laws of physics. Every engineer knows that and I'm sure you are not because you didn't know that.

Anyway, no point arguing since it is only your car that is acting this way out of all cars that is on the road. Since you are unable to accept this fact, there is no point arguing and go on doing it your way. Everyone else can do it the correct way.

Again, you have not failed to impress us with your lack comprehension in cars and rely too much on google and wiki for your defense of your statements. At first I thought it was everyone against kyheng but after a few indepth discussions with you, I realised that it is actually kyheng against the rest of the world.

This post has been edited by sleepwalker: May 26 2011, 03:36 PM

I believe you. Because you've proven to be smarter than Einstein...oh yeah, i remember you re-fill battery water once in 3 years. Yeah. I memang belip you.

Lol here we go again. Mr kybeng handing out solid advice again. He actually gave the same advice in the kia forte thread, i already told him he's gonna fry someone's car but apparently he missed that....worst case scenario the battery might explode in the person's face.

There's a reason why most modern cars have a big plastic cover on the +ve terminal on the battery, so idiots know not to touch that. If you pull the +ve and leave the -ve connected and accidentally touched the +ve cable on the chasis once it's removed there's a good chance you'll fry your car. Same with using a wrench on the +ve, the tail end of the wrench touch the chasis when working on the +ve terminal screw, you'll get the same result.

Always -ve first, putting money in your pocket kyheng.

Sorry, on this case, I never use wiki or google. It is based on experience. Who take out the wiki link, is me?
BTW, I don't know is either I just wake up from sleep or you mistype again..... This is not the first time you got me wrong and I'm sure it won't be the last also.....

No.

Disconnecting order: -ve then +ve
Reconnecting order: +ve then -ve

This is the safe way. It's your way which is not safe.

tapi for resetting ecu, do i need to remove both terminal ? or just the -ve will do ?

just the -ve will do, the drain time will vary from car to car. some takes almost a day while some 30 mins. if you want to drain fast you'll need to know how to remove the ecu fuse.

Damn this topic is hot..
Disconnect- negative first than positive(experience getting shocked when accendenly touched the positive head when trying to remove it)
Connect- positve first then negative(if you put in the negative first, and the positive after thet, i sure you, you WILL get a massive amount of SHOCK!)

Based on experience helping my brother's 93 corolla GL

understand about electricity flows is enough already to know which need to disconnect 1st. no need to gaduh2.

why not we just make a vote and majority wins...hehehe

apala.. by seeing u guys gaduh.. i'm learning things as well.. next time can try with smaller battery lor.. then see the results how.. don experiment with car battery.. do wrong.. later kaboom..

kasi cucuk obd2 scan tools la
not that expensive wat
can check for error code onn the way
win win situation

i found some sources on d internet saying we should leave d car idle for 10mins after ecu reset. There all also other sources suggest that we should drive the car at full throttle after resetting.
Which 1 is correct?