DC Down Under Epilogue: Here’s What Broke With Our Kia EV6’s Brakes
Our braking error issue, explained. Did we make the right call?
DC Down Under was a trip of contrasts. The barren desert and the two city slickers. The humble roadhouses and our shiny, cutting-edge car, an electric Kia EV6. And of course, the great success of the car crossing the desert, versus the ignominy of having to park it early due to the mystery brake issue. But just what was it that went wrong?
[Welcome to project DC Down Under, a project in which The Drive sent the indomitable Lewin Day and James Gilboy across 1,700 miles of the Australian Outback over the span of five days in a Kia EV6. Electric cars in 2022 thrive in places where there's a healthy number of public chargers; doing so across the Nullarbor Plain is another matter altogether. This is the eighth story in the series. You can read parts one, two, three, four, five, six, and seven here.]
Mo’ Brakes, Mo’ Problems
Just over a week after we said goodbye to the car in Katanning, we finally got word back from Kia Australia as to its fate. “I’ve received confirmation that one of the hydraulic pump valves inside the ABS control unit malfunctioned. The brakes still worked as they should, but this did prompt the brake alert to come up,” we were told.
The valves in an ABS system are used to modulate braking pressure to each wheel. If a wheel locks up, the corresponding valve for that wheel releases some hydraulic pressure on the brake caliper, allowing the wheel to turn for more effective braking. When active, the ABS system continually modulates the precise level of brake pressure using these valves many times per second. The system applies the maximum brake pressure possible, right on the threshold of having the wheels actually lock up.
If these valves are stuck or malfunctioning, it can affect the braking performance of the vehicle. In certain positions, stuck valves mean that the ABS system can’t activate on one or more wheels, meaning they act like regular old dumb brakes. This can lead to the vehicle pulling to one side under conditions where one wheel locks up and the others are modulated normally.
Alternatively, if one wheel’s valve is stuck in the open pressure bleed position, it means that the brakes won’t properly apply to that wheel. That can lead to the vehicle pulling to one side under normal braking.
In the minimal brake testing we did, I didn’t detect any pulling to one side or the other. It’s most likely that we wouldn’t have had full ABS activation in an emergency stop, and there may have been some pulling. However, the car would otherwise still have been drivable under normal conditions.
When I explained why we cut the journey short, the big debate was around whether or not it was the right call. I still stand by that decision. We didn’t have any information on what was wrong with the brakes, and the dash was beeping continuously demanding we stop.
Even if I knew then what I know now, I’m not sure I’d choose any differently. If we had a complete picture of what was wrong, we could have elected to limp the car. Driving at a slower speed would have minimized the risk of losing control in the event one wheel didn’t brake properly.
It would have been “cooler” and a lot more convenient to complete the trip that way. Plus, we’d have gotten great photos of us pulling the car into Perth.
However, it’s always tough to take risks like that when you’re driving someone else’s car. Plus, the incessant beeping would have driven us crazy in the three or more hours it would have taken us to get to Perth.
It wouldn’t have proven much, anyway. The hard part was getting the Kia across the desert, through towns with double-digit populations and roadhouses with even less. Getting an EV from Katanning to Perth isn’t really that hard; there are enough fast chargers dotted around that it’s pretty much routine.
In any case, it’s nice to know what really went wrong. In a way, it feels vindicating that there was a real mechanical problem. Had it been a random software glitch that disappeared, we’d have looked sillier for stopping in hindsight.
Rather than ignore the obvious signs for our own convenience, though, we thought rationally about the situation and made the difficult choice to stop. We all made it back in one piece, and we got to tell the tales of our desert journey. No matter how it ended, that feels like a win.
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