Hi. I have a 2017 RX350 question.

When I park the RX in our garage and gets to close to the wall, the pre-collision alert will come on...

But when I get to close behind the car in front of me, the pre-collision alert does nothing...

Should I be concerned?

My wife's 2018 Audi A4 pre-collision alert will come on when it gets to close to another car.

Thanks!

 

I think it has something to due with the speed when you're approaching so if you're just inching closer while at a light it wouldn't kick in.

 

Are you sure you're meaning PCS or do you mean park assist? Unless you come flying into your garage pretty quickly PCS shouldn't alert in the garage,either. My park assist system goes crazy as I pull in but I've never had my PCS system trigger going into my garage. When your system goes off, do you see the word BRAKE light up in the middle display?

 

My park assist system went off when I was too close to the car in front of me.

 

I stand corrected thank you. It's the park assist that goes off when I get too close to the wall pulling into the garage.

But still, shouldn't the PCS alert me when I get too close to the car in front of me? Say within 4 to 5 feet?

 

So many variables for the PCS to operate.
As also stated, it may or may not operate depending on conditions and sensor inputs.

Pre-collision warning:

• Vehicle speed is between approximately 7 and 110 mph (10 and 180 km/h). (For detecting a pedestrian, vehicle speed is between approximately 7 and 50 mph (10 and 80 km/h).)
• The relative speed between your vehicle and the vehicle or pedestrian ahead is approximately 7 mph (10 km/h) or more.

 

To add on, also keep in mind, PCS only reacts if it thinks a collision is imminent. For example, if you're approaching slow traffic and you're not slowing down (or braking). If the system thinks you're not going to take action (either by reducing speed or braking) then it may intervene and flash "BRAKE" in your center display and then stop the car. It is not designed to avoid every accident, nor will it. It's just a supplemental system to assist the driver. Your parking sensors, however, will beep if you're too close to a car in front of you and stopped say at a light and you inch up too close. I've had mine go off in the drive thru when i'm too close to the car in front of me and/or too close to the side of the building. PCS sensitivity can be adjusted in your center settings stack under the "gear" icon.

here is a video explaining PCS.

 

As other people noted, pre-collision is for at-speed using the radar sensor. You may be thinking of ICS which uses the sonar sensors that park assist uses.
The Intelligent Clearance Sonar function will operate when
● Engine output restriction control
• The Intelligent Clearance Sonar system is enabled.
• The vehicle speed is 10 mph (15 km/h) or less.
• There is a stationary object in the traveling direction of the vehicle and 6 to 13 ft. (2
to 4 m) away.
• The system determines that a stronger-than-normal brake operation is necessary to
avoid a collision.
● Brake control
• Engine output restriction control is operating.
• The system determines that an emergency brake operation is necessary to avoid a
collision.

 

This is most annoying when trying to pull into the garage. I, literally, have to inch forward until I'm all the way in.