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Before welding this heep, what to unground?

92DripCherokee

NAXJA Forum User
Location
Tampa, Florida
What electrics need to be ungrounded before welding?
Don't want to cause a release of the magic electronic smoke.

I'm midway into tearing out the passenger rear floorpan, going to weld in a repro stamping.

battery
PCM computer grounds to driver's fender
alternator B+, and sensing

anything else? Fuel pump, or stereo?
 
ive only ever disconnected the battery. welded up a bumper and a tire mount reinforced the rear floor pan...
 
What electrics need to be ungrounded before welding?
Don't want to cause a release of the magic electronic smoke.

I'm midway into tearing out the passenger rear floorpan, going to weld in a repro stamping.

battery
PCM computer grounds to driver's fender
alternator B+, and sensing

anything else? Fuel pump, or stereo?
Hmm never thought it, Never unhooked anything before when welding. Have welded in replacement rockers, unibody stiffeners and rear chassis stiffeners and no harm done
 
hey, that's easy enough with my marine terminals
After all this brutality on metal, the jeep has to come back to life

I actually do work from ya'lls advice here at NAXJA...and I've lived to tell about it.
I'm thinking of discharging a CO2 extinguisher into the fuel tank, before welding. Just to make the fireball a little less orange.:flame:
 
your welding on a fuel tank? if you are remove from jeep remove all sending units ect and full with water!
 
oh no, not directly on the tank, not like the bro here.
http://www.youtube.com/watch?v=tD4KiQEnxwQ
- If you've never seen a sober man weld on a fueled tank, not many of these high powered mutants are alive at any one time.

just over the front spring hanger is the closest I'll be
welding near the fuel tank, probably close enough to need cross ventilation!


The rot in the rear pan will have to wait until I have a safe, distant place to keep the fuel tank.
 
Usually, I disconnect both the positive and negative terminals on the battery. Call me over-cautious, but I once had a very bad experience arc-welding on a VW. OK, it was over 30 years ago, and I didn't know what I was doing, but it made a lasting impression!
 
Don't bother ungrounding anything, but I'd pull the fuel tank and battery and stop off the fuel lines.
 
I have talked to people that have cooked their PCM by welding, I have also talked to people who have never unhooked anything and have never had anything go weong... That said, I disconnect both bAttery terminals just to be safe, I mean you might as well, better safe than sorry and it's quick
 
Don't bother ungrounding anything, but I'd pull the fuel tank and battery and stop off the fuel lines.


dont listen to this guy... you will fry your ecu if you weld on the chassis. maybe not the first time but it will happen. unground the battery and then everything will be fine
 
Don't bother ungrounding anything, but I'd pull the fuel tank and battery and stop off the fuel lines.

If Ken is comfortable welding without ungrounding things I feel pretty comfortable. The consensus seems like if you're really worried just disconnect the battery cables. You seem worried, so unhook the battery cables...
 
dont listen to this guy... you will fry your ecu if you weld on the chassis. maybe not the first time but it will happen. unground the battery and then everything will be fine
:dunno: as long as you get a good ground on the frame and don't smack the welder into any wiring, you will be absolutely 100% fine. People have had lightning strike a car they were *driving* in, it went through the frame, axles, and tires to ground. Blew the crap out of their wheel bearings, diff carrier bearings etc but the engine continued running and the car kept driving. That's a few billion volts at a few million to a few billion amps; your welder is maybe 20 volts and a few hundred amps if you're hardcore. I'm 100% comfortable welding on my XJ with whatever the hell I want in it - including hundreds of dollars of extremely sensitive radios. Hell, I will bet you a case of beer I can throw a weld bead on a piece of 1/8 plate bolted to the side of a desktop computer case without damaging the computer internals at all.

"that guy" happens to be an electrical engineer if I'm not mistaken. Check out his threads because he is developing custom electronics specifically for our XJ's.
Correct, though I try not to toot my own horn that much :eek:. If old_man disagrees with me on welding without disconnecting stuff, I'd take it quite seriously as he has a lot more experience than I do, but I'd probably still try doing it again to test my luck. I've welded stuff on my axles, exhaust, and frame without even disconnecting the battery and had absolutely no issues; I likely will only disconnect the battery when I do new floorpans as I don't want welding heat to melt a wire and cause an electrical fire - I'd rather have it just melt a wire if I heat something up too close to one.
 
oh no, not directly on the tank, not like the bro here.
http://www.youtube.com/watch?v=tD4KiQEnxwQ
- If you've never seen a sober man weld on a fueled tank, not many of these high powered mutants are alive at any one time.

just over the front spring hanger is the closest I'll be
welding near the fuel tank, probably close enough to need cross ventilation!


The rot in the rear pan will have to wait until I have a safe, distant place to keep the fuel tank.
i kept hoping for the kaboom, and it never came:(:flame:
 
I think that the whole removing the positive battery cable comes from using a TIG welder. The high frequency arc start on these welders does weird things to electronics. I've always done it after I fried a Corvette C5 computer. Oops!! :laugh:
 
I had good luck for awhile welding on heavy equipment with disconnecting the battery. One day my luck ran out. Using a stick at 200 amp to weld a boom. There was a kaboom, and a lot of smoke. The battery blue 2/3 of the top and all the factory smoke escaped from the alternator.
 
The other key note is to place the welder ground clamp as close as possible to where you are welding and in a fashion that any possible currents would not pass thru an area that has electronics in it!
 
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