Driving home on the high way today the amber PCS light starts flashing for no apparent reason.I had been driving for about 3 hours at high speed and was in the last hour of my return from holidays when it came on.Thoughts?

 

If a continuous flash I would expect that it is indicating a fault with the system. Take it to the dealer to get it looked at.

In 18k miles I have had about 3 false activations, but each time it has only been a brief flash.

 

I'm assuming you are referring to the "PCS" light? If it's the "PCS" light, that's supposed to indicate a system error - sounds like a dealer visit is needed. After about 2400 miles, I had a false activation ("Brake!") warning go off.

 

Try to turn PCS off then on to reset it, the button is under the steering.

 

Any update on this? Did you bring it to the dealer to have it looked at? My 2016 IS350 was doing the same thing. I've had it for only 6 months and the PCS BRAKE warning went off about 7 times. I was not tailgating or stopping really fast or close to the car in front of me.