Piston Slap: VSC Light and the Puffer Fish Effect?

Looongtime TTAC commentator PrincipalDan writes:

I recently had an experience with CEL (check engine light) and VSC light (vehicle skid control) that left me scratching my head: I was on my way into Gallup (30 mile drive) and as I was getting up to speed on the highway the CEL and VSC came on at the same time. I know the CEL can be triggered by a dozen different things but seeing a constantly lit VSC was a new experience.

The vehicle (2010 Toyota Highlander) drove perfectly normally and I went on to my destination. I consulted the forums and they said the CEL would AUTOMATICALLY trigger the VSC light and that the VSC would basically be shut off by the triggering of a CEL. Dafuq!?!?!? Really Toyota?

A CEL (which could be triggered by something like an improperly tightened gas cap) will shut down one of the key components of the safety systems of the car? What’s the logic behind this? More lights means the average American is more likely to go to the dealer and get it checked out? Do all of the manufactures do this now?

BTW, my lights were triggered by a bad gas cap. Couldn’t get it to “click” anymore so I replaced — lights went away and problem solved.

Sajeev answers:

While it’s unfortunate the problem was the ubiquitous “gas cap fail,” the reality is most active handling systems tweak engine performance as part of their functionality. Be it ignition timing retardation or reining-in the electronic throttle, VSC needs an error-free engine computer. So why isn’t the car “smart” enough to leave the VSC on for seemingly irrelevant CEL warnings?

I suspect corporate lawyers (with undergrad engineering degrees) would beg to differ, risk aversion in mind. Why risk it when you might be wrong?

BONUS: A Piston Slap Nugget of Wisdom!

Think about this from another angle: consider the defense mechanism of the Puffer Fish. Now imagine a vehicle computer illuminating relevant idiot lights to save its bacon. It’s done in hopes the driver addresses the problem before it worsens, respecting your wallet, the manufacturer’s wallet, and/or our air quality. And lights can flash on/off when things are going sideways quickly. When things are hemorrhaging (literally), it’ll shut down the engine because you aren’t checking the oil pressure/level every second. That’s a smart defense strategy!

[Image: au.toyotaownersclub.com]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice. 


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