Can welding on vehicle cause electrical damage?

I'm a self-taught beginner with a Lincoln AC/DC red-box stick welder and a very basic welding question.
I made a front bumper/brush guard for my RV. My welds took and even have a
half-way decent looking bead. The bumper is now mounted on the vehicle using 8-grade bolts. I now want to add a couple tow hooks and a couple light mounts to the bumper (after thoughts). My question is...can I weld on this bumper while it is still mounted on the vehicle without damaging any of the vehicle's electrical circuits or do I need to remove the bumper completely off the vehicle prior to welding? Please excuse my ignorance but I am concerned the welding voltage may damage the batteries, fuses & other electrical devices such as the inverter/converters. Any advise from you pros would be greatly appreciated as I'm in a remote location. Thanks
WJW
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Yes it can! I don't care if anyone disagrees with me, It can, it does, it will. (With the exception of O/A of course). I always remove both the positive and negative off of any vehicle I work on and if the engine has a magneto, I pull it out. MSD, Accel, Don Zig, Mallory, French Grimes all document that damage will and can result from "any" electrical welding. Most all will deny any warranty claim showing blow-out from welding. Any reputable engine builder or chassis builder will agree in this practice. Now I am speaking only of high performance racing applications and it would be logical to assume a computerized automobile of today's production would be even more at risk. I will not work on a client's car unless it is clearly understood that if welding is needed, the electronics payload will be disconnected and reconnected and added to the billable hours. Your question is not at all ignorant, it is overlooked quite a bit and I have had many cars be trailered in after someone "welded on the roll-cage, ect" and I know right where to go and I have yet to be proven wrong. No fuse is going to stop HF destruction of an I.C. Not gonna happen. As long as there is no circuit to flow through, being interrupted by the battery terminals being open that fits 99% of the issues. Magnetos are another story. It's a pain in the ass to pull a blower and mag off and even harder on a bike but I have seen and repaired too many not to be able to speak directly to this.
Good question.
Rob Fraser
Fraser Competition Engines Chicago, IL. Long Beach, CA.

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Watch out what you weld, you can also set air bags off in a car just by poking around with a mulitmeter or a 12 volt test lamp. That would be an expensive lesson.

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Good point, I never thought of the air bags. I hear it does not take too big of a mistake to pop them off. That could be a big dollar mishap. I hear they are far from being cheap to replace... I never had to deal with one (Fortunate for me and now knocking on wood.) My Benz has 13 of them all over. I bet most cars do too. I'd hate to be the guy who screws that one up...
Rob
Fraser Competition Engines Chicago, IL. Long Beach, CA.

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On Thu, 1 Sep 2005 01:03:32 -0500, "RDF"

WOW, with that many air bags you would probably have to be rescued after a crash. LOL
--
Regards
Gordie
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Rob, you mentioned in your response that "No fuse is going to stop HF destruction of an I.C." -- a point very well taken, since the HF will certainly go straight through the fuse without popping it. But that raises a question for me: is the primary culprit in the situations you've encountered HF, as opposed to simply a current surge? I guess what I'm trying to ask is whether there would only be a problem with TIG welding using HF. Or would other kinds of welding induce HF as well? Just curious, since I'm not planning to try anytime soon -- I've always been nervous about the thought of welding on any of my vehicles ... I figure if I don't fry the vehicle, I'll probably managed to light off the gas tank :)
Thanks,
Andy

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Andy,
I have seen damage from Stick, Mig, and mostly Tig. Seems the better the technology, the more risks it generated too. Usually the damage can not be clearly identified as HF blow-out but the hardware that gets destroyed would be an easy target for such. (Ecm's and rev limiters seem to blow up first and then any sensors such as crank triggers, go on down the line.) I know that any electrical disturbance is a no-no and HF is deadly but any electrical welding can be a grief trip. Since it varies on the type of welding, but it happens on any electrical system I just start popping Molex connectors and whatever else looks like a target. Being weary of the gas tank is not a bad idea.... I had a alcohol leak in a -8 line we did not see but the plasma cuter found it. The only way we knew there was a fire is some plastic started burning that the fuel leaked over- we emptied all the Co2 and one dry chem on that one and found a little religion that day. (You can't see alky burn)
Hope that helps sir,
Rob
Fraser Competition Engines Chicago, IL. Long Beach, CA.

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RDF wrote:

Any electrical arc welding, stick, mig, tig, etc. will generate HF energy. Actually generates the whole spectrum from DC to daylight. TIG just adds an extra source of HF to get the arc established.
HF isn't a nuclear EMP, and it's not powerful enough to damage any well designed auto electronics in the levels that would be inductively coupled into the wiring harnesses. An auto is a very electrically hostile environment to begin with and all the inputs and outputs of properly designed electronics have a good deal of protection.
Recall the dreaded ignition noise on the radio, that is the VHF portion of the RF energy generated by an electric arc, i.e. the spark plugs. In the case of the spark plugs the voltages are much higher and the currents much lower than the welder, but it still produces DC - daylight energy emissions.
The main thing for welding is to minimize the opportunities for inductive pickup into the vehicles wiring harness. Keep the ground clamp as close as possible to the weld location to minimize the current paths, keep the welding cables away from the wiring harnesses, etc.
Disconnecting the vehicles battery may do more harm than good. When you disconnect the battery all of the various vehicle electrical components are still connected to ground (frame) so you still have that conduction point. The connections to the computer and other electronics if properly designed have protection devices to bypass voltage transients to ground or to the positive supply. If a positive spike is picked up on a signal line, it can still be bypassed to the ground safely if the battery is disconnected. If a negative spike is picked up and the battery is disconnected, the ability of the protection components to bypass the spike may be compromised.
If you are really concerned about damaging the ECM, disconnect the battery and then disconnect the cables from the ECM which should be quite easy on most vehicles these days. Like four simple connectors on my truck, easy to disconnect and reconnect. By disconnecting the ECM you've eliminated all points of conduction to it and it would take some incredibly strong emissions to induce damaging voltages into the pins on the connectors.
Pete C.
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FYI: Many newer vehicles have more than one computer so look to see if there is more than the ECM computer. My new truck has XM radio and On-star, they each have a computer processor in them with input from antennas to pick up RF signals, plus a computer for the interior (hidden up behind the glove box I think).
Pete C. wrote:

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Robert Ball wrote:

Yes, but you *should* be blowing up the idiotic onstar thing, and XM is an overpriced service for people who are too lazy to burn a few CDs...
Pete C.
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RDF wrote:

Most car manufacturers (European and Jap anyway) don't want you to go mear their cars with OA equipment nowadays either due to the risk of distortion (as mentioned in a previous post to the group) Years ago my old boss told me that he'd once forgotten to disconect the battery on a car he was MIG welding, he'd forgotten this because the battery was totally flat). After he'd finished welding on 2 new outer sills the car started without any problems at all. The MIG had managed to charge the battery ! Knowing my old boss he still charged an extra hours labour though
Jim
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any
but
I have welded on my 2000 f550 flatbed. (making sure I have a very good ground lead connection close to where I am welding) numerous times with no problems . (but I also had a spare computer on hand just in case.)In your case I would drill holes and mount your hooks and lights.
Bill
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Thanks for the feedback! When all you have is a hand-held drill and one pair of hands...the welding seems to be a much faster/easier/stronger solution. I think I'll just un-bolt the bumper and proceed with it that way.
WJW

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I dont know. Ive mounted many an item like those mentioned by myself with a handheld drill. Most times I would trust a towhook bolted on with grade 8 bolts over a welded on one. But its your RV. good luck.
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Surge protector that connects across the battery terminals is quite cheap, and will allow you to weld with no risk of damage to electrical parts.
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I think a surge protector is a good insurance item.
I think we will have all sorts of comments yea and nay on this due to the CAR issue.
1. Treat the car as a person. - say what you say ? - keep the welder work wire and a ground (real gnd) near the weld and never go across hinges, across the 'body' - keep it local.
The idea - if you grabbed a hot wire with your hands - do it with the right hand with the left foot raised. This then passes (if it does) current across the lungs on the right side and not the heart on the left side. Also - don't touch the live wire with the top of the head! The brain and neck bundle is at great risk then.
Oh back to the car - Don't attach to the engine body and weld the back bumper - the computer (many of them) are in-line with high current pulses (as you strike an arc and then it is lost) these can couple - two wires side by side can transmit from one to the other - and zap stuff like the 'Hi-Fi' or cruse control :-)
Keep it short and contained and life will be better. Martin (just thinking out loud)
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder
Brian G wrote:

-
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If it goes bad- $120.00hr
Fraser Competition Engines Chicago Il, 312.213.9454
All I can say is do yourself the safety of unplugging "any" electronics you can isolate. I do this for a living and if I had not repeatedly repaired cars in from the chassis shop that were in PERFECT running condition before taking frame current I'd be skeptical but it pays my bills pretty well so I guess I'll stand firm. Yes, by all means keep the clamp as close as possible and sometimes a double-jumper clamp is a great idea too. I pulled out a BBQ'D $11,000.00 ignition system that was trash after being welded near and I have paperwork form both Mallory and MSD denying claims as "Electrically damaged equipment, not covered and clearly stated in installation and maint. documentation" Proof's right there. Two mags, a crossover, Denenbear delay, timers and everything on Pete Holman's 2004/2005 Top Fuel Avenger(s) I build engines and drive lines for. He threatened with a lawyer and they told him to bring it on. He bit the bullet and had to replace everything because the chassis shop guys would not listen to me and tore the note off the windscreen. I walked away clean. He sued the chassis shop which I will not name but he lost in court and was advised an appeal was a lesson in futility. I'd argue this further but I'm not going to waste my time. Do as you will but the caveats are there. It's risky, it's done daily but a roll of the dice and I have a disclaimer on my contracts that has language directed at this issue.
Rob
Fraser Competition Engines Chicago, IL. Long Beach, CA.

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