Kia and Hyundai brake fluid leak recall

[Ash]

Found out about this :

https://www.nhtsa.gov/press-releases/consumer-alert-kia-and-hyundai-park-outside

(we do have a couple Hyundai's in the extended family)

 

As an engineer i am interested in understanding the details of what's actually going on. Some things in the report don't really add up for me :

 

1. Most "petrochemical" fluids are not electrically conductive. It's not clear to me how a fluid leak leads to a short circuit

Heck, even mild salt water is not conductive enough for a short circuit that would set anything on fire at 12V (assuming contact area typical of pins in a connector, it would just electrolyse till it dries up)

Or they mean that a 2nd unrelated electrical failure in a nearby component (a direct metal short circuit, creating overheated conductors or a spark) might ignite the leaking brake fluid ?

What's the ignition source in a car that's standing parked, ignition off, and cold ?

 

2. With brake fluid leak i would be primarily concerned about losing the ability to brake the car. Apparently the leak is so tiny that this haven't been an issue as i dont see it mentioned. (and the cars have been around for a few years with the defective components, so plenty of time to leak unnoticed)

If i get it right, the leaked fluid pools inside the case of some module, where it stands waiting for a short circuit to ignite it ?

 

[GMcD]

A recall has been out for a year. My dad had it done on his ix35 a few months ago. (Pretty sure it's related)

.https://www.check-vehicle-recalls.service.gov.uk/recall-type/vehicle/make/HYUNDAI/model/iX35/year/2013/recalls

[Dyslexic Viking]

There have only been 22 cases on several million cars. And there have been no crashes or people who have been injured, but still they choose to call in cars to be sure and all the cars are older models. So I think it's good that they take the bad pr and cost and call back cars to be sure nothing bad will happen.

GM killed over 100 people with a faulty ignition switch, so worse things could happen.

https://en.wikipedia.org/wiki/General_Motors_ignition_switch_recalls

[SiC]

Contaminated brake fluid is conductive. It's how the brake fluid testers work to determine moisture content. 

That leaking into an ABS control module could easily trigger the gate side of a MOSFET driver. Could cause a pump/valve to run at maximum capacity for a long period (so getting very hot). Alternatively if a H-Bridge/phase driver (especially used if brushless motor on the pump) then if both halves are driven from a short then crowbar across the supply rails. Device will then quickly get very hot until it lets the smoke out with the possibility of igniting the brake fluid while it's at it. 

Brake fluid is also high flammable. A lot of car garage welding/blow torch heating/cigarette smoking videos you see that go up in flames really quickly is often down to catching brake fluid alight. 

The smaller fuse is presumably to blow before the internals get hot enough from a short to cause ignition. Possibly rated well below the maximum device current rating to ensure it won't be in the region of destruction and thus excessive heat/subsequent ignition.