These are all relative potentials of course. Remeber - electron flow theory of how current flows negative to positive. With the presence of ECMs and other low voltage/low current capable components, handling and other processes have updated to keep pace.Ĭheck out the amount of voltage generated by a static discharge spark you get crossing the room in winter and douching something metal, it takes a surprising amount of voltage to jump from your finger tips to a object - that's the built up potential (charge) seeking a neutral potential (ground or less negative than your finger). There just was not the need for the precautions. Prior to the early 80's, when ECMs made their first appearance, there were few static discharge sensitive components (transistor radios, Chysler transistorized/electronic ignition?). I am not at work today, but if it is not GM propritary information I can post up imperical data, if you let me know for what you are asking. What kind of stats are you looking for? Anicdotal accounts are not objective. Not throwing it out there because some tech writer thinks it it is a verified failure mode. You may think this is just my opinion, and you'd be correct but it is an informed opinion based upon working as a Powertrain Control Service Engineer since 1991. Think about the guy that can't be troubled to use a 9V memory saver when disconnecting the battery (or can't even be bothered to disconnect the battery) before working on your car. After returning the circuit to normal and operating the vehicle through multiple ignition cycles and days, the vehicle will set a P0171 /P0174 Lean Fuel Trim. No apparent symptoms, no MIL, no pending DTCs. One test that will not give immediate sensor failure is to short +12V to the HO2S low reference (signal return) circuit. My first hand experience with something similar is testing GM car/truck ECM circuits destructively to validate the service information my group writes at the GM proving ground. It's like crossing a busy street with your eyes closed, yes you can get away with it for a while. And like the lightening analogy, damage can and will take different forms.ĭisconnecting the negative battery cable is the quickest and safest way to open the vehicle's entire electrical system and isolate all connected components from transient spikes that can be generated by static discharge from simply sliding across a vinyl seat and touching a component's circuits/pins OR from spikes and/or induced EMF from electrical (not gas) welding.ĭon't get me wrong, I do think you can weld on a car/truck and 'get away' without short/long term damage but don't be surprised if there are unexplained symptoms down the road. It may very well take days, weeks for the 'welding with the battery connected' damage to reveal itself. "would customers return to the muffler shop or does anyone make this connection if indeed the is an issue ?" Click to expand.I see you are saying what I've been thinking as I read through the posts.
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