Is it true that if you do any mig arc or tig welding on your truck the current from the welder will fry the PCM and or the IDM?

 

a guy where i work puts in gooseneck and fifthwheel trailer hitches all the time and doesn't unhook the bateries. maybe he's just lucky or he just gets a really good ground, i think that may have something to do with it more than luck.

 

I have alwats believed this and have always been told to unhook the batts when mig welding.

I had an 89 I was welding the exhaust and when I was done the truck wouldnt start ended up being pcm I didn,t unhook the batts when I was welding could be coincidence but ever since then I unhook the batts when I weld on my truck.

 

Well I was just about to start telling you all the times Ive welded on mine or another truck then I realized that I had the batteries out of the trucks to weld what ever it was I was welding. I didnt fry anything so I guess it might be a good idea to disconnect the batts.

 

I would say the possibility is always there but I have never had an issue and have welded on lots of vehicles.

 

Disconnecting the batteries is probably a good idea as a precaution, but I never do it and I've welded on mine a half dozen times or so with no problems.

 

I've never seen an exhaust shop disconnect batteries to put on exhaust.

The current will take the shortest least resistant rout from point A to point B.
If you choose a poor ground, you could send voltage though the harness. Choosing a good grounding point would make the difference IMO. The voltage will never "stray" around to things like PCM or other electronics unless it was allowed to due to where your welding, and how you choose your ground. Just remember to always keep your ground away from wires, and try and keep the ground closer to what you are welding.

High powered arc welding, I would suggest disconnecting the batteries, but why would you want to cut the frame rail while trying to weld?
Get my drift?

 

I have never fried anything while welding on a vehicle, but I guess it's a good precaution to disconnect the batteries

 

Thanks. Glad to hear it. I have heard of people going so far as to remove the PCM and I don't think that is a easy thing to do on our trucks. Will disconnect the batts to be safe.

Latter....

 

Ditto that, in fact welded on it a little last night and she is still running....

 

electricity is lazy, it follows the fastest path of least resistance to get from point A to point B. unless you clamp the ground to the pcm then you wont fry it. i cant count the number of vehicles that i have welded on with out issue. never fried anything. the only time i would consider disconnecting anything would be if i was welding under the dash for any reason since it is right next to the pcm, but the batteries would do nothing, i would remove the pcm

now we do have some vehicles at work that the people want everything disconnected..... all battery cables, not just the ground, all computers to be disconntected and removed..... its a pita.

 

That sounds a lot like airport security coon.

 

you sound just like a new guy i once told to disconnect the batteries when welding on his own personal car. he was welding in a new muffler. he said "it will be fine the clamp is right near the weld".

10 minutes later we were calling junkyards for a PCM.

its not the current from the welder that cooks electronics. electricity definatly goes in the shortest least resistant path, the current is going from the wire or stick, to the ground. its not going on a scenic tour of you trucks wiring harness.

electronics do not like strong static, or strong radio signals. have you ever heard a shop radio that is playing next to a welder? that noise is whats frying the electronics. since static is just electric saturation without a set ground point, it will go on a scenic tour. also, the radio waves are radiating away from the arc site, and will cause noise on a completed circuit.

so.......chances are, you wont have a problem if you dont disconnect the batts, BUT.......i have seen it happen a few too many times to believe its coincidence.

who is lazier, electricity, or you??? pop off the ground cables, it takes less than a minute.

 

By what your saying, and the way you explained it. Disconnecting the battery cables will make no difference what so ever to killing a PCM or any other sensitive electronics.

Current doesn't need a battery to be plugged in to travel, nor does it need a battery to create static, noise or any other feedback related to welding.
The only time you will create a problem while welding is if your welder some how is grounded to whatever you have your car on. A light hung underneath that is getting feedback from the welder all the way though the wall. Or from the lift your using to lift the car, because you've somehow grounded out the lift to the welder in some way.

If you can manage to explain to me how disconnecting your batteries can make a difference in how the current and static and what else you have explained will flow, then I will possibly believe you.

 

disconecting the ground cable from your battery will not protect your pcm, like you just stated, listen to the radio near a welder, yet they are on different outlets on different circuits. the "noise" from the welder doesnt care if the ground cable is disconnected or not, there are tons of other chassis grounds on the vehicle that the damage can travel through and take out your pcm. Please, dont call me lazy. If you want to get technical then you need to do as i stated before, the pcm and all electronics in the vehicle must be completly isolated to be 100% safe of damage, so simply disconnecting the ground cable from the battery is lazy.
also, when you disconnect the 50 pin pcm harness you are supposed to have you body grounded with wire before you touch it. technicly a static jump from your body can fry the pcm.