Lasting Damage From Intentional Short Circuit?

[mongolodeon]

I believe you should mention it to them. They will likely better understand what they may see on FDRS (ford scan tool) when they hook it up to do the software updates. It makes it much easier on the technician to know what has happened previously. Cars these days have so much information it can be very overwhelming if they don't know the story behind what they are looking at. I don't feel you were bashing anybody really. Just a concerned customer, which I fully understand. I don't believe he would have done any sort of damage contrary to what some others have implied. Glad to hear you are going to have an appointment this time coming. I wish you had a better experience first time around which would have saved you the second one. Hope they can solve your issue rather quick and painlessly. I don't see why not though. Apim updates can take a couple hours so be patient and all will be good.

I really appreciate your help here @Darrell78 , and everyone else's on this thread for that matter. I don't know what I'd do without this forum!

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[RossRR]

I really appreciate your help here @Darrell78 , and everyone else's on this thread for that matter. I don't know what I'd do without this forum!

Modern microcircuits can be very sensitive to transient voltages (the spark) and can be susceptible to latent failures if exposed but not properly protected within the circuit. A latent failure could fail within weeks or could last years before finally giving up the circuit. Manufacturer's that work with microelectronics spend a lot of money ensuring their factories are free of transients with special conductive floors and work benches and requiring workers adhere to specific clothing guidelines. Since automobiles have been notorious for generating transients, I would expect the computer circuitry has built in protection, but only the manufacturer knows for sure how robust their computers are.

This is what HammaMan in post 15 was alluding to.

 

[Ranger621]

I understand the theory but I don't understand why he would do that to discharge any caps. I would think just leaving the battery cable off, the caps would bleed down quickly. Shorting out caps, I have done many times. But at the cap terminal, not at the supply.

Just removing the battery cable, it can take as much as half an hour for residual power stored in capacitors to dissipate. As an electronics tech for over 40 years,, I can say what he did was common practice to discharge the caps immediately. This does not hurt anything. If there was an additional battery source still connected to the circuit, worst case it may have blown a fuse. Anyone who works on any high power equipment knows to do this so they don;t get zapped by te caps. The Ford tech did nothing wrong.

 

[Kanuck]

Just removing the battery cable, it can take as much as half an hour for residual power stored in capacitors to dissipate. As an electronics tech for over 40 years,, I can say what he did was common practice to discharge the caps immediately. This does not hurt anything. If there was an additional battery source still connected to the circuit, worst case it may have blown a fuse. Anyone who works on any high power equipment knows to do this so they don;t get zapped by te caps. The Ford tech did nothing wrong.

Let's just say...you would not be working on my truck...BTW.... I have been in automation for just short of 50 years...

 

[Snakebitten]

But there IS an auxiliary battery.
So arguably, you can't claim the Ford tech "did nothing wrong".

And while I'm not one to pile on in most situations, it's just not OK for the Ford tech to not know his product line. There's a Blue Oval on his shirt, afterall.

 

[Xman]

What caused the "puff of smoke"? Something had to transition to create it.

 

[HammaMan]

What caused the "puff of smoke"? Something had to transition to create it.

Likely vaporized parts of the jumper wire or points where it contacted. Typical arc plasma doing its thing. Could have also heated up the wire itself.

 

[HammaMan]

Just removing the battery cable, it can take as much as half an hour for residual power stored in capacitors to dissipate. As an electronics tech for over 40 years,, I can say what he did was common practice to discharge the caps immediately. This does not hurt anything. If there was an additional battery source still connected to the circuit, worst case it may have blown a fuse. Anyone who works on any high power equipment knows to do this so they don;t get zapped by te caps. The Ford tech did nothing wrong.

Great way to get an arc flash going. Sounds like you've been real lucky. The absolute last thing you do is short a circuit like that. First things first is to verify / discharge (or charge for that matter) with a resistor / verify.

Fortunately for those who have lackadaisical training, modern components are trying to be 'idiot proofed' by design with bleed resistors being integrated into HV systems. You will find NOTHING about shorting a circuit back onto itself in any of the manuals out there. It's verification. When a contactor welds closed, extra precaution is required. There's even additional circuitry being added to also alert of a contactors position being off nominal as well as warning a circuit still contains voltage.

Incandescent test lamps with redundant indicators are sufficient to provide a visual indicator to lack of voltage / drain status of LV systems.

 

[v8440]

I was just going to say, though hammaman beat me to it, that making the short he did but through a 100 or so Ohm resistor would be sufficient to discharge anything not still battery powered in seconds while completely preventing any big current transients in the event that a battery was still connected somewhere.

 

[Gros Ventre]

Today I picked up my 2022 PowerBoost Limited from a dealership and found that they had not solved a problem where the SYNC system cannot check for a software update (which is a separate issue altogether). They brought the master tech out to the parking lot and he attempted to reset a module(s) hoping that it would do a complete enough reset to cause SYNC to fully reboot and then be able to check for an update OTA.

To do this he disconnected the negative cabling from the 12V battery and left the positive side connected. Then he took a small wire with alligator clips at both ends and clipped one end on the positive terminal (still attached to the battery post) and with the other end tapped it on the negative wiring (which was not attached to the battery post). There was a small puff of smoke and we heard some clicking from the engine compartment and the master tech was clearly surprised by this, remarking that "there must be another battery" and then mumbled about how there's another very small battery for the GPS antenna but that it shouldn't have caused what occurred. He didn't try again, so it was just the one time and it was fairly brief.

He then told me to start the truck and it started normally, but SYNC had not done a full reboot as he had intended and the software update page still just hung, trying to check for an update. He then said to bring the truck back for another appointment and he'd do a manual software update of SYNC using the shop laptop. The truck behaved normally for a few short trips after that.

Has anyone ever heard of something like this and is it possible that the technician did something that damaged the truck (electrical system, hybrid or 12V batteries, other sensitive modules) but won't be apparent right away? I would never think to do something like that but given that the service advisor brought him over and introduced him as a master technician and the most knowledgeable person in the service department regarding the PowerBoost and SYNC systems I deferred to his experience and expertise- yet I am disturbed by his reaction and surprise at what happened and it was clear that it wasn't the result he expected.

Just want to make sure my truck is not now compromised in any way as a result. I also plan to bring it to a different dealership to try to resolve the software update issue.

If you have a PowerBoost... there sure is another battery and its a full up 12vdc battery though smaller than the engine battery. It's under the Pax rear seat. It's in parallel with the main battery unless the truck is in the engine start mode when the two are split apart with the smaller battery serving to maintain system voltage while engine is cranking. I cannot believe he didn't know this... but then my dealership (fall of 21 so PBs were quite new) didn't know that either and I had to teach them... another story.

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