Welding with the ecm in the truck

[kmanrsss]

I'm in the process of swapping am 83 cab onto an 87 chassis. As i need to swap all the wiring anyways am i better off welding in the tranny tunnel and other parts before installing the ECM? Is there any precaution to take or is just disconnecting the battery enough? thanks

[Da67goatman]

I have done some welding on the body, without disconnecting anything.  Just keep the ground as close to the spot your welding as possible, good rule to follow regardless.

[Iann128]

Do not disconnect the battery, and keep the welder ground as close to the welding as possible. Electricity follows the easiest path. Clean the spot where the ground clamp goes and you will not have any issues. The battery being connected acts as a buffer.

[Cabcorner]

        Always disconnect the negative from the battery when you weld on a vehicle . If you should forget , these trucks are usually pretty forgiving .

[choptop]

The key thing is, like everyone has said, clamp your ground as close to your worl as possible. I work on industrial electronic engines daily and this practice saves alot of head ache down the road. That said, the mechanical system can be damaged by improper gounding techniques as well. ran a failure analysis of a main bearing that had arc marks on it. The welder putting the exhaust in grounded to the frame, instead of the exhaust flange, and it arced thru the mains