# Disconecting the negative terminal **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2013, 5:40pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373 "2013-03-19T17:40:02Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [March 20, 2013, 2:20pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/21 "2013-03-20T14:20:58Z")
> [@echo7tango](#): > > And yes, could have resulted in injury. Could? I think did - just not external ones. ---
**Author:** ![JBDivmstr](https://avatars.discourse-cdn.com/v4/letter/j/b4bc9f/32.png) [@JBDivmstr](https://boards.straightdope.com/u/JBDivmstr)\ **Post date:** [March 21, 2013, 2:23am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/22 "2013-03-21T02:23:00Z")
> [@Machine\_Elf](#): > > 😕 Why? He appeared to be complicit in the stunt. I think not… :dubious: It looked like the guys that ‘set that up’, made it a point to do it without him knowing. There are numerous examples of ‘pranks’ like that on Youtube. Granted, in some of them, everyone knows what is about to happen. In the one I linked to, it looks as if the guy had no idea that was about to happen. :eek: Which is also irrelevant to the OP. The point of providing the link was to show an example of just how powerful (and dangerous) an exploding air bag can be. Just sayin… ---
**Author:** ![JBDivmstr](https://avatars.discourse-cdn.com/v4/letter/j/b4bc9f/32.png) [@JBDivmstr](https://boards.straightdope.com/u/JBDivmstr)\ **Post date:** [March 21, 2013, 2:55am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/23 "2013-03-21T02:55:26Z")
And just for the record… I’ve been in two seperate accidents and had the airbag deploy. :eek: (Both times, in a 2003 Chevy Silverado 1/2 ton PU) The first time was a high speed impact, a drunk driver swerved across three lanes into my lane, I didn’t have any time to react (brace for impact/hit brakes/swerve). Impact speed was approx. 60 mph. I drive setting as far back as is comfortable from the steering wheel, with the wheel tilted almost all the way down. The airbag deployment was barely noticeable. (Meaning, I didn’t ‘feel’ it when it hit me in the chest.) The second time was a ‘low speed’ impact, approx. 15 mph. I was pulling a trailer and there had just been a rain shower, making the streets slick. Due to inattention on my part, I didn’t notice the light change. I applied my brakes, but due to the extra weight of the trailer, I slid into the intersection and hit a PU truck that was going thru the intersection. The frame horn that the impact sensor is mounted in (in that particular model of PU, and probably most other PU trucks) impacted the rear wheel of the truck that I hit. When the airbag deployed, it struck me in the chest hard enough to take my breath away. It felt like someone had slapped me in the chest, open handed, as hard as they could. I can only imagine that if it had hit me in the face, I would have been sporting a bloody nose and two black eyes. The moral of the story… Set well back from the steering wheel (as far as is comfortable) and tilt it down (if you have that option) as much as possible. 🆒 ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [March 21, 2013, 5:09am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/24 "2013-03-21T05:09:24Z")
> [@JBDivmstr](#): > > And just for the record… I’ve been in two seperate accidents and had the airbag deploy. :eek: (Both times, in a 2003 Chevy Silverado 1/2 ton PU) > The first time was a high speed impact, a drunk driver swerved across three lanes into my lane, I didn’t have any time to react (brace for impact/hit brakes/swerve). Impact speed was approx. 60 mph. I drive setting as far back as is comfortable from the steering wheel, with the wheel tilted almost all the way down. The airbag deployment was barely noticeable. (Meaning, I didn’t ‘feel’ it when it hit me in the chest.) > > The second time was a ‘low speed’ impact, approx. 15 mph. I was pulling a trailer and there had just been a rain shower, making the streets slick. Due to inattention on my part, I didn’t notice the light change. I applied my brakes, but due to the extra weight of the trailer, I slid into the intersection and hit a PU truck that was going thru the intersection. The frame horn that the impact sensor is mounted in (in that particular model of PU, and probably most other PU trucks) impacted the rear wheel of the truck that I hit. > When the airbag deployed, it struck me in the chest hard enough to take my breath away. It felt like someone had slapped me in the chest, open handed, as hard as they could. > I can only imagine that if it had hit me in the face, I would have been sporting a bloody nose and two black eyes. > The moral of the story… Set well back from the steering wheel (as far as is comfortable) and tilt it down (if you have that option) as much as possible. 🆒 Well, first let me say that I’m glad your accidents weren’t more serious, and that you described them quite nicely. The only thing I’d like to say is that people should not waste any of their time being ‘scared’ of airbags, you should be scared of automobiles! IOW an airbag is only as powerful as it needs to be, but that that need is fairly strong simply because the energies involved in even a low speed car accident are far beyond anything the human body has evolved to tolerate. The big, cushy bag of air (nitrogen actually) is only going to hit \*you \*as hard (or less) than your _face_ would be hitting the steering wheel, or windshield, or dashboard etc. without it! ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 21, 2013, 6:05am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/25 "2013-03-21T06:05:35Z")
::: Sigh::: So much incorrect /partially correct info in this thread. > [@Mdcastle](#): > > There’s this warning: “disconnect the negative terminal of your car battery before any work or the airbags will explode in your face and you will die” > > Has this actually happened? Is the airbag to dumb to not differentiate between driving into a semi vs trying to fix the heated seat or changing the ash tray bulb? > > As common as it is to work on a car, why not have a main disconnect for the car, and a battery backup for the radio? Umm, year make and model that had this exact wording? I’m in the business for 40+ years and I have never seen a warning that was this full of shit. Do you disconnect the battery before working on the airbag system? Absolutely. Do we disconnect the battery before repairing a wire to the left tail light? Hell no. > [@Kevbo](#): > > Also, it is the negative terminal because it is easy to short the wrench to ground when loosening the terminal, and that will/may cause big sparks/hot melty stuff/exploding battery if you are doing the positive one, but nothing at all if it is the negative. Once the negative is off, it is then safe to work on the positive unless the vehicle has multiple batteries,(Diesels, jumpy low-riders, kidney massaging stereo equipped customs) then you need to take all the negatives off before touching any of the positives. This is correct about why you disconnect the neg first, and reconnect it last. The part about multiple batteries is a A) pretty rare in the wild, and B) usually there is a single ground that can be disconnected. > [@NitroPress](#): > > Never touch any electrical component of a car without disconnecting the ground first. At best, you won’t have to replace pointlessly blown fuses. At worst, you won’t burn off your ring finger or set fire to the car. It’s not a lawyer thing, it’s a don’t-be-fucking-stupid thing. Turn off the power to that circuit, then it is safe as houses. > [@Mdcastle](#): > > Well, would it be save to unbolt the seat or change a light bulb if the switch was off with the battery connected if I’m not touching any live wires? The seat needs power to slide back and forth to get at the bolts. The biggest danger changing a bulb with the key on is the new bulb will get damn hot quickly and you might burn your fingers. The seat is a special case see below. > [@gotpasswords](#): > > Good question… I wouldn’t disconnect the battery just to change a light bulb, but if your seat has side-impact airbags (normally, this is identified with an “AIRBAG” tag sewn into the seam) all bets are off. If you’ve got [airbags in the seats](http://www.proseatcovers.com/help/airbags), investing in a shop manual for the car might be prudent. > > It’s probably OK to move the seat back and forth to access the bolts, but then you’d need to determine the proper procedure for disconnecting the airbags. I think the days where you could set off the steering wheel airbag just by smacking a sensor are behind us, but you can still set them off with an accidental short circuit or some othe accidental “perfect storm” event that makes the car’s computer think “Crash!” Started off correct, then you took a hard left into urban myth with the smacking the sensors statement. Many (not all, but many) airbag systems are live if the key is in position 1 (accessory) or position 2 (key on, does not require the engine to be running for the system to be live). If you leave the key on, and disconnect an airbag connector, you will set a fault code and turn on the warning light. No you can’t kill the light by disconnecting the battery. If you have the key on and go to work on the car with any type of impacting tool (air or electric) you run the risk of a deployment. I know a guy that was doing a major service on a car. He forgot to turn the key all the way off (left it in accessory) He went to change the fuel filter located under the car (just about under the driver’s seat) He went to undo the mounting bolts with his 3/8" impact and there was a very large BOOM. Both front air bags, both seat belt pretensioners deployed. It seems the fuel filter bracket is only about 8" or so from the SRS control unit. The whacka-whacka-whacka of the impact sounds just like hitting a brick wall to the SRS unit, so it deployed. Turn the key off the system is safe. Leave the key on it isn’t. Now let’s get back to the undoing the seat. You have to have the key on in many cars to move it to access the bolts. Cordless impact wrenches are becoming very common even with home mechanics. So picture this. Car has key on to move passenger’s seat. Seat gets moved all the way back, key is left on and our hero reaches in with his cordless impact to undo that inner front mounting bolt. What he doesn’t know is the SRS control unit is located in the center console about 3" from where he is about to apply an impact. The passenger airbag is going to hurt. :smack: but wait it gets worse. I have a picture posted in my shop bulletin board from a local Toyota dealer. Tech had the interior gutted and was removing the SRS control unit. He forgot the key was on and lifted the unit up and turned it over to disconnect the electrical connector. The SRS sensed a rollover and blew the side curtains, and side impact bags. If he had had the key off, it would have been safe. Battery disconnected even safer. > [@Hail\_Ants](#): > > All airbag wiring is usually wrapped in day-glow yellow casing so as not to be messed with by any mechanic, amateur or pro alike. While it’s highly unlikely that you’d ever set one off, it’s far from impossible if you don’t disconnect the battery. All you’d have to do was stick a live continuity or other hot 12V probe into the right (or wrong!) one of its wires, and _ **KA-BLAMMO!** _ It’s a bit of an exaggeration, but remember TWA Flight 800? Conspiracy nuts aside, that’s essentially what happened to it, a short circuit back-fed high voltage into a low voltage fuel tank sensor. Very bad day… Orange actually. Although many newer cars just have the airbag wiring integrated into the harness with no wrapping. Also you would have to supply both power and ground as neither is connected all the time. Not impossible, but unlikely. So stabbing a live continuity tester into an airbag wire won’t set it off, as many of these wires are shielded, you could very well short the power and ground to the airbag together resulting in a warning light and possibly a very expensive repair bill. [story about warnings in repair manuals] Back in the day I worked on Jaguars. The Jag repair manual had three warnings [ul] [li]Disconnect the battery[/li][li]Depressurize the fuel system[/li][li]Drain the cooling system[/li][/ul] It seemed like every repair procedure had 1, 2 or sometimes all 3 warnings at the beginning of each repair. After a while reading these same three warning you get to silly season. So one of us would start a job and the talk in the shop when something like this Tech 1 “Hey did you remember to Depressurize the battery?” Tech 2 (guy working on car) “No but I disconnected the cooling system” Tech 3 “No, no, no you are supposed to drain the battery, not depressurize it.” OK, it was a location story, you had to be there. ---
**Author:** ![JBDivmstr](https://avatars.discourse-cdn.com/v4/letter/j/b4bc9f/32.png) [@JBDivmstr](https://boards.straightdope.com/u/JBDivmstr)\ **Post date:** [March 21, 2013, 9:56am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/26 "2013-03-21T09:56:16Z")
> [@Hail\_Ants](#): > > Well, first let me say that I’m glad your accidents weren’t more serious, and that you described them quite nicely. The only thing I’d like to say is that people should not waste any of their time being ‘scared’ of airbags, you should be scared of automobiles! IOW an airbag is only as powerful as it needs to be, but that that need is fairly strong simply because the energies involved in even a low speed car accident are far beyond anything the human body has evolved to tolerate. The big, cushy bag of air (nitrogen actually) is only going to hit \*you \*as hard (or less) than your _face_ would be hitting the steering wheel, or windshield, or dashboard etc. without it! Thank you, and yes, I agree that people shouldn’t be scared of airbags. 🆒 The OP’s question was, should a person disconnect the battery to keep from inadverdantly setting off an airbag. And as others have pointed out, it’s not something that should be worried about, \*\*\*if \*\*\*the person working on the auto has some basic working knowledge of auto electrical systems. 😉 And upon recollection, the smell that was produced by the bags deployment was just… _ **nasty** _! (For lack of a better adjective. ☹ ) ---
**Author:** ![JBDivmstr](https://avatars.discourse-cdn.com/v4/letter/j/b4bc9f/32.png) [@JBDivmstr](https://boards.straightdope.com/u/JBDivmstr)\ **Post date:** [March 21, 2013, 9:58am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/27 "2013-03-21T09:58:25Z")
> [@NitroPress](#): > > I suppose there’s a level of electrical service or repair below which the need to disconnect the battery would be unnecessary, but having blown fuses while changing minor light bulbs, I will usually do it for anything involving wires. It’s one of those cases where the minute or two of time invested helps insure against multiplying the duration and difficulty of the job greatly. +1 😃 ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [March 21, 2013, 1:17pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/28 "2013-03-21T13:17:45Z")
> [@Rick](#): > > ::: Sigh::: > So much incorrect /partially correct info in this thread. > […] > > Turn off the power to that circuit, then it is safe as houses. Maybe you can do that in a 1968 pickup; good luck turning off all circuit and adjacent power in a modern vehicle. Cars don’t have anything like circuit breakers that cut all power in a particular part of the vehicle; even pulling the fuse for what you’re fixing leaves live circuits all around it. But this is America; people are free to damage and set fire to their vehicles any way they like. Unless they’re leased. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 21, 2013, 2:56pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/29 "2013-03-21T14:56:14Z")
> [@NitroPress](#): > > Maybe you can do that in a 1968 pickup; good luck turning off all circuit and adjacent power in a modern vehicle. Cars don’t have anything like circuit breakers that cut all power in a particular part of the vehicle; even pulling the fuse for what you’re fixing leaves live circuits all around it. > > But this is America; people are free to damage and set fire to their vehicles any way they like. Unless they’re leased. Well I don’t know what your qualifications are but I’m an ASE master automotive technician, I have 45 years of automotive experience, I have done technical training for over 20 years, 15 of which were as a technical trainer for a car manufacturer. I am currently a service manager for the largest Hyundai dealer on the west coast. What are your qualifications? I suspect my qualifications far out strip yours, so I can say with a fair amount of confidence that you are wrong about this. Yeah there are some circuits that have stay alive power to them with the key off. Things like the clock, radio, engine control module but hardly do you have live circuits all over the car. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 21, 2013, 3:08pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/30 "2013-03-21T15:08:24Z")
What Rick said both times… 🙂 Anything past light bulbs, get a manual. Me? I take it to the shop. Well if I had anything new I would. I have learned to not stab sharp things into wire bundles. YMMV ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [March 21, 2013, 3:24pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/31 "2013-03-21T15:24:24Z")
> [@Rick](#): > > What are your qualifications? About 40 years of working on everything from Model A’s to F1, including rotisserie restorations and on-my-back-in-the-rain repairs. More importantly, working with a lot of amateurs and DIY’ers. So you’re super-certified? Fine. Do it your way. But I think that recommending Joe Weekender not take some reasonable precautions against mistakes and ignorance is misplaced. > [@GusNSpot](#): > > I have learned to not stab sharp things into wire bundles. Cars are full of bare connection points that can be crossed with a casual slip of a tool. You don’t have to be trying to stab anything to slip or drop something. Especially if you’re less than ASE-certified. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 21, 2013, 4:10pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/32 "2013-03-21T16:10:32Z")
In case you Hadn’t noticed we are in GQ looking for factual answers to questions, not you opinion. The fact is you are wrong. Both about the amount of circuits that remain live but also about the amount of connectors and the claim that they are bare and will short with a careless drop of a tool. The question was is it necessary to disconnect the battery before doing any electrical work on the car. The factual answer to that is a resounding NO. Should a DIYer consult a service manual? Always a good idea. Most people don’t know as much about auto repair as they think they do. Several posts in this thread are my cite. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [March 21, 2013, 9:41pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/33 "2013-03-21T21:41:58Z")
Something else to consider: Even if you don’t injure yourself when accidentally setting off the airbag, unless your car is fairly new and worth a lot of money, once you’ve triggered an airbag you may have quite easily sentenced your otherwise perfectly good vehicle to the junkyard! Once an airbag deploys the car’s computer is not going to let it start or run or do much of anything. Which means you’ll have to either: [list=A] [li]Replace the airbag and get the computer reset, which will be \*\*\*very \*\*\*expensive (easily more than a used car’s total value!)[/li]or [li]Not replace the airbag but then somehow ‘hotwire’ the computer into thinking that you did (or again it won’t let the car function)[/li][/list]I know that for A, airbags are extremely expensive to buy (in the thousands) and will most likely require dealer installation (I can’t picture any backyard or independent repair shop even attempting such an install). And as for B, I don’t know if that’s even possible to do (hotwire a car’s ECU to ignore the airbag’s status). ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [March 21, 2013, 9:52pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/34 "2013-03-21T21:52:21Z")
> [@Rick](#): > > The question was is it necessary to disconnect the battery before doing any electrical work on the car. The factual answer to that is a resounding NO. And that’s not your \*\*\*opinion \*\*\*because…? The \*\*\*factual \*\*\*answer is that I’ve never seen a DIY manual or many maker shop manuals that don’t begin by telling the worker to disconnect the ground before any electrical work. So if your \*\*\*opinion \*\*\*is that that’s excessive or unnecessary, we can all live with that. Or at least anyone careless enough to do electrical work without cutting the juice - 120V or 12V - is. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 21, 2013, 10:45pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/35 "2013-03-21T22:45:59Z")
> [@NitroPress](#): > > And that’s not your \*\*\*opinion \*\*\*because…? > > The \*\*\*factual \*\*\*answer is that I’ve never seen a DIY manual or many maker shop manuals that don’t begin by telling the worker to disconnect the ground before any electrical work. I can back up my statements with factory service manuals. You know the ones that are written by the guys that designed and built the car in question. Without a doubt they are **the** authority on how to repair a particular car. You appeal to authority can’t go any higher than that. The car maker is the Supreme Court in the matter and your appeal has lost. Sorry but you are wrong. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 21, 2013, 10:47pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/36 "2013-03-21T22:47:10Z")
> [@Hail\_Ants](#): > > Something else to consider: Even if you don’t injure yourself when accidentally setting off the airbag, unless your car is fairly new and worth a lot of money, once you’ve triggered an airbag you may have quite easily sentenced your otherwise perfectly good vehicle to the junkyard! Once an airbag deploys the car’s computer is not going to let it start or run or do much of anything. Which means you’ll have to either: > [list=A] > [li]Replace the airbag and get the computer reset, which will be \*\*\*very \*\*\*expensive (easily more than a used car’s total value!)[/li]or > > [li]Not replace the airbag but then somehow ‘hotwire’ the computer into thinking that you did (or again it won’t let the car function)[/li][/list]I know that for A, airbags are extremely expensive to buy (in the thousands) and will most likely require dealer installation (I can’t picture any backyard or independent repair shop even attempting such an install). And as for B, I don’t know if that’s even possible to do (hotwire a car’s ECU to ignore the airbag’s status). Your kidding, right? ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [March 21, 2013, 11:08pm UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/37 "2013-03-21T23:08:41Z")
> [@Rick](#): > > I can back up my statements with factory service manuals. > You know the ones that are written by the guys that designed and built the car in question. > Without a doubt they are **the** authority on how to repair a particular car. > You appeal to authority can’t go any higher than that. The car maker is the Supreme Court in the matter and your appeal has lost. Sorry but you are wrong. You have got to be fuckin’ kidding me. **The question was asked by someone inexperienced enough to have to ask it…** and your response, all hand-waving arrogant pomposity, is to tell them to **disregard a basic safety rule** stated at the beginning of every formal service procedure I’ve ever read, and one confirmed by the experience of anyone who’s got any number of hours working on cars - a rule that will keep them from blowing a fuse, burning wiring, setting fire to the car or possibly losing a finger to ring-burn. This isn’t one of your fellow grease-jacks with enough experience to know better, it’s an **amateur** , as are most who have commented in this thread. Those of us with decades of hard-won experience owe beginners and amateurs every courtesy of safety instruction, not jackass he-man bullshit. This is so breathtakingly arrogant and irresponsible I call for a moderator to take notice of it before someone assumes you know what you’re talking about and pays the price for it. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [March 22, 2013, 4:53am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/38 "2013-03-22T04:53:16Z")
My tongue won’t let me bite it any longer. 😛 > [@NitroPress](#): > > Never touch any electrical component of a car without disconnecting the ground first. This is just ridiculously overstated and broad, even as advice for an amateur. > [@](#): > > …having blown fuses while changing minor light bulbs, I will usually do it for anything involving wires. Though if you can’t replace a light bulb without blowing a fuse I can see why you think it’s helpful. > [@NitroPress](#): > > Many circuits in modern cars are hot all the time, and the ones that aren’t are adjacent to ones that are. > [@](#): > > … even pulling the fuse for what you’re fixing leaves live circuits all around it. > [@](#): > > Cars are full of bare connection points that can be crossed with a casual slip of a tool. You don’t have to be trying to stab anything to slip or drop something. I can’t say I’ve run into cars where this has been an issue. I’m wondering what kind of vehicles you’re working on and what kind of circuits you’re dealing with, but mostly I’m wondering just how clumsy are you? I do a fair amount of electrical work on a variety of modern (and older) cars and I just haven’t had these kinds of problems, nor in most cases even seen the potential for them. > [@Rick](#): > > Do you disconnect the battery before working on the airbag system? Absolutely. Do we disconnect the battery before repairing a wire to the left tail light? Hell no. Now this makes sense. Some circuits have danger potential, and some don’t. Most rank amateurs can indeed replace light bulbs without popping fuses or burning up their cars, and have no need to disconnect the battery for such simple tasks. > [@NitroPress](#): > > This is so breathtakingly arrogant and irresponsible I call for a moderator to take notice of it before someone assumes you know what you’re talking about and pays the price for it. Overreact much? **Gary T** , ASE certified Master Automotive tech with 40 years professional experience repairing automobiles, not rotisseries. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 22, 2013, 4:54am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/39 "2013-03-22T04:54:50Z")
Is changing the oil a formal service procedure? Do they recommend in writing to disconnect the Negative terminal before proceeding? Oh, you meant anything electrical? Or just electrical formal service procedures? If I find even one manual that does not say what you claim, then we have to drop “EVERY” from your argument. You might say “MOST”… You do not remove your rings before doing electrical work even with the negative disconnected? Bad example that because while you are around the battery …oops !!! I have been reading Rick on this board for YEARS… I’ll go with what he says, thankyouverymuch. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 22, 2013, 4:56am UTC](https://boards.straightdope.com/t/disconecting-the-negative-terminal/653373/40 "2013-03-22T04:56:44Z")
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