Welding Car Disconnect Battery. I have repaired cars where someone grounded a. When you disconnect the negative terminal on the car battery you break the loop at that point.
Open this panel to access the ECU. You disconnect the battery and all is good. There are a few vehicles now where the manufacturers DO require disconnecting the battery on newer vehicles last two to three model years but along with that they also require disconnecting several harnesses as well.
I have been told by a few guys to always disconnect the negative battery cable for fear of messing up the vehicles computer or alternator before welding on a truck.
What is more important is proper placement of the returnwork lead. I think more cars get upset disconnecting and reconnecting the battery abs airbags ECU etc than welding on them. To disconnect the car battery before beginning a TIG weld perform the following steps after securing safety goggles and some gloves for hand and eye protection. I have never disconnected a battery havent had a problem.