Does it matter if I disconnect the - or + on battery to reset ECU??
04-01-04, 02:21 PM
#1
Pole Position
Thread Starter
Join Date: Aug 2002
Location: California
Posts: 249
Likes: 0
Received 0 Likes
on
0 Posts
Does it matter if I disconnect the - or + on battery to reset ECU??
I was wondering if it makes a difference if I disconnect the NEG. or POS. on the battery if I wanted to reset the auto leveling system computer? Thanks in advance to any help.
04-01-04, 02:28 PM
#2
Lead Lap
Join Date: Aug 2003
Location: California
Posts: 551
Likes: 0
Received 0 Likes
on
0 Posts
Always disconnect the positive. I'm sure removing the ground will have the same effect, but It's good practice to pull the positive, as that is ultimately what you are trying to do...disconnect the power.
The following users liked this post:
DocCocina (05-27-20)
The following users liked this post:
DocCocina (05-27-20)
04-01-04, 02:44 PM
#6
Well from a safety point of view, I think it does. If the + is disconnected and somehow you bridge (say with an open end wrench) from any ground to the + terminal, BIG NASTY SPARK. If the - is disconnected and you bridge from any ground to it, its just like reconnecting it, little or no spark, and if you bridge from any ground to the +, nothing.
George
George
And that's what all the shop manuals say too.
Trending Topics
04-01-04, 04:40 PM
#11
Master Thread Closer!!
iTrader: (33)
Join Date: Jul 2002
Location: Waipahu, Waikele, HI
Posts: 9,859
Likes: 0
Received 9 Likes
on
9 Posts
Originally posted by Carpe Diem
Also its easier to get to the negative. You don't need to wrestle with that plastic cap.
George
Also its easier to get to the negative. You don't need to wrestle with that plastic cap.
George
Pete
04-01-04, 09:05 PM
#14
Lexus Test Driver
Join Date: Dec 2002
Location: California
Posts: 1,159
Likes: 0
Received 0 Likes
on
0 Posts
take off negative, but when you reconnect, reconnect with the positive first. disconnecting incorrectly can cause battery explosions. or so they tell us in autoshop, maybe just to scare us.
04-02-04, 08:58 AM
#15
Lead Lap
Join Date: Jul 2003
Location: California
Posts: 607
Likes: 0
Received 0 Likes
on
0 Posts
To summarize above:
When removing cables, remove negative first, then positive. If you just want to reset the ECU, removing only negative is good enough.
When installing cables, install positive first, then negative.
When the negative battery terminal is connected, most bare metal parts of your car act like the negative terminal of the battery.
If you were to disconnect positive first and accidentally touched a bare metal part of the car, it would cause a spark which could ignite any flammable gasses your battery may be emitting (obviously don't touch the positive terminal with the same wrench you're disconnecting the negative terminal with).
Disconecting the negative terminal first is safer because while disconnecting the negative terminal, you only really need to worry about not touching the positive terminal. As soon as the negative terminal is disconnected, the only way to complete a circuit (cause a spark) while disconnecting the positive terminal is to touch the negative terminal of the battery.
To answer the question about whether removing positive only or negative only is good enough, yes removing any one of the two terminals is good enough, BUT it is much SAFER to remove negative only.
When removing cables, remove negative first, then positive. If you just want to reset the ECU, removing only negative is good enough.
When installing cables, install positive first, then negative.
When the negative battery terminal is connected, most bare metal parts of your car act like the negative terminal of the battery.
If you were to disconnect positive first and accidentally touched a bare metal part of the car, it would cause a spark which could ignite any flammable gasses your battery may be emitting (obviously don't touch the positive terminal with the same wrench you're disconnecting the negative terminal with).
Disconecting the negative terminal first is safer because while disconnecting the negative terminal, you only really need to worry about not touching the positive terminal. As soon as the negative terminal is disconnected, the only way to complete a circuit (cause a spark) while disconnecting the positive terminal is to touch the negative terminal of the battery.
To answer the question about whether removing positive only or negative only is good enough, yes removing any one of the two terminals is good enough, BUT it is much SAFER to remove negative only.
Last edited by PhantomZX; 04-02-04 at 09:00 AM.