Why you should remove the negative battery terminal before doing ANYTHING!!!!

Hi, Probably you don't even know basic Ohm's law or Kirchoff's or Tevnin Norton's theorem, etc. If you want to debate, email me directly. Let's compare our CV first.

Reply to
Tony Hwang
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tony, this is usenet - "credentials" don't mean shit. just stick to the facts.

fact 1 - batteries don't "surge". period. some [reactive] peripherals can do it, unless protected. in cars, they all are. dome lights are not reactive.

fact 2 - ohmic behavior dictates that battery voltage drops as current increases, not the other way around.

fact 3 - ecu's are "idiot proofed". per #1, a dome light has no reaction that could possibly cause a problem, even if the ecu was unprotected.

conclusion: either address reality or move on.

Reply to
jim beam

No but a direct short could cause a problem in the item shorted. In the case of some vehicles that could be the BCM if they use it for things like an interior light timer/dimmer (close door and dome light stays on for a bit) Shorting that circuit cause problems.

Yes BUT take a chunk of wire and toss it across the battery. Measure the battery voltage. It likely won't cause a voltage drop as it heats up and melts.

VERY WRONG. ECUs are easy to kill if you are not paying attention. My SOP in the body shop is to pull the ECU on anything that rolls in for panel work. One good zap from a welder can kill the ECU without being near it.

Reply to
Steve W.

You are utterly without a clue. Best keep quiet.

Reply to
dizzy

On about 92 and up:

The dome light is c>> Gary L. Burnore wrote:

Reply to
Refinish King

Hey, RK, how ya doin'?

I wanted to ask you something a while ago, but I forget.

At any rate, right. The DL is connected to the BCM, which MAY have a connection to the ECM.

Reply to
Hachiroku

Boy, am I glad that my newest vehicle is an '83...

JT

Reply to
Grumpy AuContraire

rubbish.

"likely"??? dude, it /definitely/ does! grade school science class.

eh? welding is a whole different ball game to shorting a fuse protected light circuit. welding is done at voltages and currents in excess of those seen in vehicle operation, and is accompanies by all kinds of radio frequency noise, both from the spark and the welder, depending on welder type! yes, it's good to disconnect the ecu while welding. no, shorting a light circuit doesn't replicate those conditions.

Reply to
jim beam

yes, which is not the ecu!

Reply to
jim beam

Maybe he reversed the polarity of the Bogon Flux ?

Reply to
Andy Dingley

Hey, I can even _spell_ Thevenin

Reply to
Andy Dingley

I talked to him last night. He says he wants you to come out and tell him why his Pathfinder won't start after changing the dome light...

Reply to
Hachiroku

I'm doing great!

Thank you.

If anyth>

Reply to
Refinish King

Reply to
Refinish King

It could be a coincidence?

Maybe there is another problem.

Reply to
Refinish King

On Nov 11, 3:48 pm, "Steve W." wrote:

Guys, guys... go get a schematic and find out if the dome light is in the same circut as the ECU. Even if it is, I don't think the changing of the bulb is what caused the problem. I do think that whatever caused the light to function intermittantly MIGHT have cused the ECU problem. Either way, if the light was working sometimes, that would tell me that there was nothing wrong with the bulb. Funny thing about light bulbs... they either work, or they don't. The filament is either complete, or it's not. It doesn't go back once it's blown. Okay, so if there's a short, it would be either in the fixture, or in the wires going to it. Furthermore, That's what fuses are for! I've done it many many times. Shorting things out and blowing fuses and replacing them again. The fuse opens the circut in the event of a short before ANYTHING gets damaged (unless the fuse is either disregarded, or replaced with a fuse of a higher amperage). And furthermore, since we're on the topic of fuses, this is the whole reason that things like dome lights and tail lights and headlights and radios and ESPECIALLY ECU's are all on thier own circuts with thier own fuses. Kind of insurance, if one thing blows a fuse, you don't lose everything at once. I do agree with the titlehead of this issue, being "disconnect the negitive before working". But this rule is mostly in place because sometimes people like to play with the wires and accidently drop the exposed end of a hot wire onto the bare frame of body of the vehicle. The result can be a blown fuse at minimum, or a small fire at most (I've been there, too). However, I regress (and conclude), the dome light bulb cannot be the reason for ECU problems. ECU's may or may not be "idiot proofed," but they are not on the same circut as the dome light, the dome light cannot cause "power surges" and niether can anything else on a vehicle, and even if anything were to happen, the fuses would have caught it. Case Closed. Go get a new ECU, and re-wire your dome light. quit griping about crap that is not relevant. The more you gripe, the more other people despise you, and the job still is not done.

Reply to
fury45iii

Yeah, but we're talking a Nissan here! I've seenthings in Nissans I've never seen in other cars.

And, he said the glass was broken. How it even lit without burning out is a mystery!

Reply to
Hachiroku

A welder and a dome light are vastly different things. An arc welder generates a HUGE reactive voltage spike when striking the arc, and that spike can wander all over the entire vehicle and fry sensitive electronics and not-so-sensitive things, too, like alternator diodes. Standard procedure there is to disconnect the battery whenever doing any welding on the thing. Shorting a dome light will NOT generate any sort of spike. Period. You need a coil to generate spikes, coils like those found in starters, alternator rotors, ignition coils. You might as well try to generate a spike by disconecting and reconnecting the battery.

Dan

Reply to
Dan_Thomas_nospam

Hmmm, Lamp filament is a tiny coil, LOL!

Reply to
Tony Hwang

with an air core and virtually no inductance. if you have instruments that can measure any voltage spike you get from a coiled bulb filament, i'd love to see your readings.

Reply to
jim beam

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