Resetting the computer
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There are two main reasons. One is if your truck throws a code (check engine light on). Resetting the computer will get rid of the code. Sometimes the cause can be transient and resetting is all it needs. If the code returns the you must address the problem.
The second reason is if you add a performance modification. Resetting the computer puts it at the neutral (unlearned) state so it can relearn the new characteristics of the performance mod. This will happen eventually anyway but is suppose to happen faster with a reset.
Resetting is done by disconnecting the positive battery terminal and turning on the headlights (although they won't light). People differ in how long you need to do this but 30mins should be fine. I do it quickly by touching the positive terminal to the negative terminal (works every time) but in the past I have come under attack for recommending this proceedure. What this does is discharge all the power from the diodes in the memory.
The second reason is if you add a performance modification. Resetting the computer puts it at the neutral (unlearned) state so it can relearn the new characteristics of the performance mod. This will happen eventually anyway but is suppose to happen faster with a reset.
Resetting is done by disconnecting the positive battery terminal and turning on the headlights (although they won't light). People differ in how long you need to do this but 30mins should be fine. I do it quickly by touching the positive terminal to the negative terminal (works every time) but in the past I have come under attack for recommending this proceedure. What this does is discharge all the power from the diodes in the memory.
Last edited by WLF; Jul 27, 2002 at 09:06 AM.
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Every engine modification and light install instructions I have ever read begins with DISCONNECT THE POSITIVE BATTERY CABLE. I have yet to hear of anyone being blown up... I don't know if this works by disconnecting the negative terminal.
BLOWN UP
BLOWN UP
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From: Dallas
Blowup?.........
the battery contains hydrochloric acid as the chemical reation occures between the plates of each cell they release hydrogen gas.......hydrogen gas?....the gas that was used on the hindenberg zepplin....blow up?....oh yeah....big time with severe burns,blindness...should i go on?
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From: Under the flightpath of old ORD 22R
WLF outlines the reason of why very well,
I will have to say that unhooking the pos side of the batt is not going to release any hydrogen into the air.
BTW hydrogen needs a catalist to ignite, oxygen is not it. A lit smoke is, but not oxygen. If it was water would be a dangerous combustable, and we would all be walking time bombs ( the body is something like 80 % water ).
I will say though, when I take my batt out of wing for the winter, I unhook the neg side first. This way if I cross the pos side on something ( large screw driver to frame ) is is not going to take out something like the computer.
I also take off the neg side first when replacing a batt, just b/c I have been known to be a clutz at times, and slip with a screw driver.
If you are careful about not shorting pos to the frame, it does not really matter which order you take them off in.
I would never have thought about taking of pos lead , and shorting it to ground, but that is a quick drain for any diode or cap in the system. I do not see where this could be a problem in a circuit ( as long as you take it off the batt first of course ), and I have never read the threads where he came under attack for this, and why others say not to do this.
As far as electronic circuits 101, this cannot lead to damage. In school this is how we dischard caps in a circuit when working on them, so you did not get bit by them, again with power removed from the system.
Same goes for discharge of a gun on the back of a monitor, when these still were fixed on site years ago, you used 2 screw drivers to short the high voltage gun in the back of the tube to ground so you could take it out and replace it when the monitor had a problem with pixel layout.
BTW hydrogen needs a catalist to ignite, oxygen is not it. A lit smoke is, but not oxygen. If it was water would be a dangerous combustable, and we would all be walking time bombs ( the body is something like 80 % water ).
I will say though, when I take my batt out of wing for the winter, I unhook the neg side first. This way if I cross the pos side on something ( large screw driver to frame ) is is not going to take out something like the computer.
I also take off the neg side first when replacing a batt, just b/c I have been known to be a clutz at times, and slip with a screw driver.
If you are careful about not shorting pos to the frame, it does not really matter which order you take them off in.
I would never have thought about taking of pos lead , and shorting it to ground, but that is a quick drain for any diode or cap in the system. I do not see where this could be a problem in a circuit ( as long as you take it off the batt first of course ), and I have never read the threads where he came under attack for this, and why others say not to do this.
As far as electronic circuits 101, this cannot lead to damage. In school this is how we dischard caps in a circuit when working on them, so you did not get bit by them, again with power removed from the system.
Same goes for discharge of a gun on the back of a monitor, when these still were fixed on site years ago, you used 2 screw drivers to short the high voltage gun in the back of the tube to ground so you could take it out and replace it when the monitor had a problem with pixel layout.
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From: Under the flightpath of old ORD 22R
Hindenburg facts
Might want to read this. NASA research hd found out years later that the skin of the aircraft was what origionally ignited, and then was what in turn caused the Hydrogen to ignite. The fire was found to not be caused by the Hydrogen itself.
http://www.vidicom-tv.com/tohiburg.htm
Quote from one of the pages :
In many years of research, a NASA scientist at Cape Canaveral has discovered its real cause: Neither the hydrogen in the hull nor a bomb was to blame, but a special fabric for the outer skin that, when ignited, burns like dry leaves.
http://www.vidicom-tv.com/tohiburg.htm
Quote from one of the pages :
In many years of research, a NASA scientist at Cape Canaveral has discovered its real cause: Neither the hydrogen in the hull nor a bomb was to blame, but a special fabric for the outer skin that, when ignited, burns like dry leaves.
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Good thread SSCULLY, and not just because you agreed with me.
I too have heard of batteries "BLOWING-UP" but have not seen this in real world, well maintained vehicles.
It probably is a good idea to disconnect the ground wire first. I burned the entire top of the motor on a 67 Barracuda (cried for a whole day) when I dropped a wrench and grounded the positive battery terminal to the aluminum gas line (that was fun). Tought me real fast to disconnect the battery when I work on my engines.
I too have heard of batteries "BLOWING-UP" but have not seen this in real world, well maintained vehicles.
It probably is a good idea to disconnect the ground wire first. I burned the entire top of the motor on a 67 Barracuda (cried for a whole day) when I dropped a wrench and grounded the positive battery terminal to the aluminum gas line (that was fun). Tought me real fast to disconnect the battery when I work on my engines.
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From: Maryland
o.k. guys I will explain.
Car batteries do blow up I have seen it (My brother for instance) they have warnings all over them that they can go boom.
If you read in the manual about how to "Jump start" properly they tell you to hook the positive 1st then hook the negative to a part of the frame or engine "Away from the battery" to avoid sparking.
Hence, when you remove the positive terminal first you get sparking not to mention the posability of frying your computer and other electrical components.
You are correct that removing the positive cable will not release any gas, BUT if the battery happens to have a crack in it that you don't know about. (Which can happen with a properly maintained vehicle too)
If you live in the east,southeast and south you will have plenty of catalyst to go boom. It's called humidity. (like Scully said "WATER")
If you take off the negative cable first there is little to no sparking and you don't send any harmfull power surges through your electrical system. In the "OLD DAYS" you didn't have a computer and sensitive electronics on board to worry about.
I am a little surprised at this thread. I thought it was well documented at the reasons you NEVER pull positive first. I have even seen other threads on this forum about it.
Oh well, do what you wish, be safe, and enjoy your truck!
Peace.
Car batteries do blow up I have seen it (My brother for instance) they have warnings all over them that they can go boom.
If you read in the manual about how to "Jump start" properly they tell you to hook the positive 1st then hook the negative to a part of the frame or engine "Away from the battery" to avoid sparking.
Hence, when you remove the positive terminal first you get sparking not to mention the posability of frying your computer and other electrical components.
You are correct that removing the positive cable will not release any gas, BUT if the battery happens to have a crack in it that you don't know about. (Which can happen with a properly maintained vehicle too)
If you live in the east,southeast and south you will have plenty of catalyst to go boom. It's called humidity. (like Scully said "WATER")
If you take off the negative cable first there is little to no sparking and you don't send any harmfull power surges through your electrical system. In the "OLD DAYS" you didn't have a computer and sensitive electronics on board to worry about.
I am a little surprised at this thread. I thought it was well documented at the reasons you NEVER pull positive first. I have even seen other threads on this forum about it.
Oh well, do what you wish, be safe, and enjoy your truck!
Peace.
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From: Seabrook,NH
It is the sparks created when removing or connecting a cable that has the potential for causing an explosion with a bad battery. You will get sparks from either connector. It does not matter which one you remove first. Jumping is different than resetting your computer. Jumping indicates that one battery may be dead or weak. It is weak or dead batteries that produce the most gas and would be the most dangerous. A weak battery will draw a lot of current which produces those large sparks. You connect pos first when jumping so that you can complete the circuit with the neg cable at a grounding point away from the battery to keep any sparks away from possible gas.
Diodes do not store a charge. Capacitors do and the ones in the computer are small and will be discharged in less than a minute with the headlights left on. 30 mins is overkill. Wait 5 minutes if you feel the need to be sure.
Diodes do not store a charge. Capacitors do and the ones in the computer are small and will be discharged in less than a minute with the headlights left on. 30 mins is overkill. Wait 5 minutes if you feel the need to be sure.
Last edited by Norm; Jul 29, 2002 at 11:17 AM.
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From: Maryland
yes you will get sparks from removing either the pos or neg cable. in general you will get much less sparking when you remove the negative cable first. especially if you do not remove it smoothly.
stay safe and remember that sparks can ingnite more than just a leaky battery!
stay safe and remember that sparks can ingnite more than just a leaky battery!