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

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.

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.

"Steve W." wrote in news:fh80s0$kq$ snipped-for-privacy@aioe.org:

jim beam wrote;

Yes,it will.That battery has internal resistance,and a short will draw a lot of current and make for a heavy V drop.(the same happens every time you start your car;there are specs for battery Vdrop while cranking.)

You are utterly without a clue. Best keep quiet.

On about 92 and up:

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

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.

Hi, Internal resistance is very small value. Against dead short it's not a big factor. Cranking is not a dead short situation. Once I dropped a pair of plier across heavy industrial battery terminals. The plier litterally evaporated.

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

JT

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.

what is it then? state the number of ohms. typical honda civic battery.

it is when it's the largest resistance in the circuit!

and?

sure. and how much did the voltage drop?

yes, which is not the ecu!

Maybe he reversed the polarity of the Bogon Flux ?

Hey, I can even _spell_ Thevenin

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...

Anybody that says a short on a voltage line can't hurt an ECU has never worked on computers.....

I'm doing great!

Thank you.

If anyth>

It could be a coincidence?

Maybe there is another problem.

He said there was a spark when he tried to remove the bulb. The bulb's glass was broken, and he tried to grab it without touching anything else, but there was a spark, and when he tried to start the truck...nothing.

He had it towed to a Nissan dealer. They're trying to find a used ECU and told him that before doing ANYTHING electrical with the truck he should...

disconnect the negative battery terminal...

(Next week he's removing the terminal and installing a Negative Terminal Shut-off...)