[Diy_efi] Welding on cars w/ ECU's??

[Perry Harrington]

Chris,

The problem is with the ECU being voltage spiked by high current AC or DC from the
welder.

Now, any competent welder won't cause that to happen, but if you have your ground
return far away from the welding location it has a much higher possibility of zapping
the computer.  If the computer is between the ground and the head in the circuit, it
can seen voltage spikes that are well outside the normal operating range.

If you put the ground near the welding location, it localizes the current flow and
greatly minimizes the potential for problems.

Also, I wouldn't be suprised if there were some EMI concerns too.

--Perry

On Fri, Jan 31, 2003 at 02:26:33PM -0600, Chris Spies, ATI ProCharger wrote:
> Can anybody explain to me why it is you can not (at least the aftermarket manufacturers prefer that you not) weld on a vehicle while the ECU is connected (electrically) to the vehicle?  It seems that muffler shops weld on vehicles with factory ecu's all day long without trouble, however I have heard many horror stories of damaged aftermarket ECU's and ignition boxes when somebody neglected to disconnect the harnesses?  I have never really been given a good answer, I just follow the rules and hope to avoid disaster...
> 
> -thanks
> -Chris

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-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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