Joe Pfeiffer wrote:
Randy writes:

I've done it both ways, main thing is to ground to what you're
welding, if you're welding exhaust ground to the exhaust. If you're
welding on the bumper ground to the bumper. If you're welding on the
exhaust and you ground to the frame, you never know what's rusty and
what path the current will take. If a nice path by way of the o2
sensor through the ECM and back to the frame is the way the current
travels then you just smoked the ECM.

Finally, an explanation for how welding can damage electronics that
makes sense! Note that the way to avoid it has nothing to do with the
battery.

Yeah, that makes a lot of sense. If you weld the exhaust, which will
likely have a very good electrical connection to the engine, but might have
a poor connection to the frame because of rusty brackets and rubber engine
mounts, and you ground to the frame instead of to what you are welding, the
path the current finds from the exhaust to the frame might well be through
many places you didn't want it to go including your drive train and
bearings as well as through sensitive electronics. I could see how that
could be a common error people could make which could lead to bad issues if
the engine wasn't well grounded to the frame.

--
Curt Welch http://CurtWelch.Com/
http://NewsReader.Com/