If I disconnect my PCM can I still start my truck? I know the PCM controls the tranny and some gauges and stuff, basically what I want to do is disconnect it, start the truck and use my onboard welder on my own truck without messing up my computer, then when I am finished, plug it back in and go.

 

I've never disconnected the PCM or ECM on any piece of equipment. Main thing is, keep the ground clamp as reasonably close to the work as possible. Make sure it has a good ground. Never had a problem.

The PCM regulates the alternator voltage.

 

Yes, it will start and run just fine with the PCM disconnected. You won't have a tach, speedo, charge, grids, cruise or some automatic tranny funtions.
Won't hurt anything at all.

I used to weld without disconnecting anything till the one time I fried the $900 electronic ignition on a Toyota when welding the tailgate. Now I always disconnect the battery ground, don't know if this is enough but haven't damaged anything else.

 

I don't think I can disconnect my ground because then my welder wouldn't work. it uses voltage from the battery to excite the field and for welding from my little alternator.

 

What kind of welder is it? How does it work?

 

its basically an old ford alternator belt driven off the engine, and a switch sends battery voltage to the field windings, then hook your positive cable to the positive output of the alternator and the ground to your ground, and you have to play with the engine RPM depending on the thickness of the material. its basically a 100 amp stick welder.

 

remove your ground from the truck, not the welder... use the batt. for the portable!!

 

the welder is ground to the chassis all the time through the frame of the alternator.