How to disconnect battery?

[supra]

Hi, I need to disconnect battery to reset ecu.

my question is which terminal do you disconnect first?

+Ve or -Ve first?

would I need to disconnect both in order for the whole car to open circuit?

any safety precautions when do so?

Car battery provide 12V power right? instead of 240V at home! so if any thing goes wrong, i wont become a :ghost: right!!! :headspin:

[supra]

I just found something my self. Thanks for reading.

Link

[Bax]

So your all good bloke? Anymore questions?

[predator]

lol.. no you won't go toasty..

Always best to disconnect the positive first and leave the ground to provide an earth. Soon as you disconnect the positive the power will be disconnected.

When putting it back connect the ground first, then positive.

It may make some sparks when you connect back the positive nerminal, but its generally ok.

[supra]

are you sure about +ve first? cause the article said the -ve first, I am confused! doing it right now...

[ferni]

yeah always take negative off first, that way there is no ground to get the power out...

if you undo the positive, there is a chance of grounding the spanner from the positive terminal to the body of the car which will create a circuit and end up going back to the negative side of the battery... bad

if you disconnect the negative side, then you can't create a circuit...

if you just want to disconenct the battery, just one terminal is enough, no need to take both off... unless you are removing it or charging it etc...

[sewid]

I have always removed the -'ve first for the same reason as Ferni.

For example to reset the ECU you would remove the -'ve lead, pump the brake pedal and reconnect the -'ve.

[supra]

I have just finished the reset the ecu and took it for a drive! BEAUTIFUL, I have yet to take it for a long drive. Tommorrow, if all goes good, I will make a new thread about it. Any thanks all... I have removed both terminals! man, the job took 1 hour plus cause my amp is fixed to the back wall! have to removed that to access the battery!

[Sumo]

Ferni:

you only need to disconnect one terminal to charge a battery.

[Sumo]

Make sure you turn the charger off at the power point before disconnecting too.... I have seen a battery explode from hydrogen gas and a tiny spark.

[paulr33]

when you disconnect the one side press the brake pedal a few times to discharge any power. the ecu can keep the settings in memory and the car will have enough power for about 12 hours to survive without the negative connected. the old school way was to remove the negative and leave it overnight but the quick way is to disconenct it and press the brake pedel, this will use any left over power in the system

[Samuel Leonard]

when you disconnect the one side press the brake pedal a few times to discharge any power. the ecu can keep the settings in memory and the car will have enough power for about 12 hours to survive without the negative connected. the old school way was to remove the negative and leave it overnight but the quick way is to disconenct it and press the brake pedel, this will use any left over power in the system

You'd need to turn your ignition to on before pressing the brake pedal though because brake lights don't come on with no key in the ignition I don't think?

[89CAL]

Ummm yes they do. Brake lights come on regardless of if your keys are in the car or not

[eiresgaus]

You'd need to turn your ignition to on before pressing the brake pedal though because brake lights don't come on with no key in the ignition I don't think?

You don't need to do this, + they probably knew this back in 2004 too

[Samuel Leonard]

You don't need to do this, + they probably knew this back in 2004 too

HAHA! i really really need to start reading how old a thread is that i'm replying to. done this a few times now just using search. lol