Has it really ever happened??? ECM and welding

00gyrhed · Sep 22, 2006

I have read on many occations from that you should never weld on your vehicle without disconnecting the battery. The theroy being that you could damage the ECM or even the battery. I have been welding on vehilces for over 30 years. Professional welders weld on thier trucks every day and do not disconnect the battery. I usually disconnect the battery to be safe, but I forget almoxt as often as I remember. I have never had a first or even second hand bad experience. Like a lot of these things its always a freind told me. Or it happened to a guy I know, but the story teller never really saw the results.

Has anyone actually ever lost an ECM due to welsing ontheir vehicle?

It takes my ECM about two weeks to relearn everything.

NYLES · Sep 22, 2006

Not exactly what you wanna know but MSD does say disconnect the computer box. Nothing about the battery.......wonder if it makes any diff what polarity you weld in?

Better yet how would you weld on your rig with an onboard welder with either dissconnected?

00gyrhed · Sep 22, 2006

exactly;D

SaddleUp · Sep 22, 2006

NYLES said:
Better yet how would you weld on your rig with an onboard welder with either dissconnected?

If you check out these systems they are isolated entirely from the main battery. (The last one we used we literally pulled 2 batteries out of other rigs and used them to power the onboard welder)

As far as damaging the ECM I've welded on mine quite a bit with the battery connected and it hasn't damaged it. It's one of those do as I say not as I do deals though. I always tell people that ask that the battery needs to be disconnected whenever your welding but personally I don't.

tejayandtina · Sep 23, 2006

I've seen it happened to a brand new Autocar truck at work. Truck ranweird and had all kinds of gremlins. Replaced the ECM and runs fine.

SaddleUp · Sep 23, 2006

FWIW I have seen stuff fried on vehicles from welding. It's pretty common if for instance you try to ground to the frame and weld the body. If there isn't a good ground between the body and frame it will search for a path which could be an electronic component. Usually it's just smaller diameter wires though that end up melting.

wildbill · Sep 23, 2006

In over 40 years of welding on autos I have never undone the battery. The most important thing is to have a very good ground right next to were you are working. Hope this helps good luck.%) %) %) Bill %)

;D

Broncobowsher · Sep 23, 2006

Sorry, no first or second hand knowelge of welding killing a computer or battery. I deal with it all the time as well. Just keep the ground close to the work and be sure it is the same part. I have welded the exhaust of a computerized car to fix a leak, while it was running. I don't ever remember seeing a muffler shop disconnect a battery either.

Actually disconnecting the battery could be harmfull. The battery is a giant capicator, it absorbs spikes in the eletrical system. The only thing that would make sense would be to disconnect the computer, but even that isn't on the recommended list by the overcautious OEMs.

scsm76 · Sep 23, 2006

I fried a computer on a Volvo semi while welding on his mobile home trailer tongue. He had ripped half the tongue off by letting the trailer cheat of the edge of the road. The truck was blocking the road for about eight hours while the other truck with the other half placed his section and came back to move the broken one. Alot of people were upset since the there was only one way in and out.
Funny thing is I asked the driver if he wanted to disconnect the tongue from his hitch for this reason and he refused. Only time I have heard of it happening though.

BroncoMarc · Sep 23, 2006

My buddy was trying to weld the steering arm back onto his passenger side knuckle on his heep last month at Paragon with his premiere power welder. We saw smoke coming from the drivers side. Somehow it put a hole in his stainless brake line and the fluid was smoking. It did the same thing later on the passenger side, but we could see where there was an arc between the brake line and the shock. We never did figure out why this happened. He had a good ground right next to where he was working. Maybe it was trying to find a shorter path to the battery?

Jeepster · Sep 23, 2006

Are you welding with a service truck? If so your fine. If its another vehicle your welding on I would disconnect Negative lead.

Has it really ever happened??? ECM and welding

00gyrhed

Bronco Guru

NYLES

Bronco Guru

00gyrhed

Bronco Guru

SaddleUp

Bronco Guru

tejayandtina

Sr. Member

SaddleUp

Bronco Guru

wildbill

Old Bronco Guy

Broncobowsher

Total hack

scsm76

Bronco Guru

BroncoMarc

Sr. Member

Jeepster

Bronco Guru

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