Park Assist Beeper

[Joe in NY]

All of a sudden my Parking Assist is shutting itself off and won't come back on. If it's off it's supposed to re-set to "on" every time you start the car. What happens is it will be on until I put it in reverse and as soon as I do it beeps once and the message on the overhead console says the park assist is off. Sometimes it will come on and stay on for a couple of days but once it's off I can't get it to come back on no matter what I do. Any suggestions?

The car is a 2005 Town Car.

 

[tixer]

I've seen cases where the individual sensors fail, and I wonder if your car isn't "failing the self-test" and disabling them as a result.

I know that when they are working, you should be able to have a friend (set the e-brake and) throw it in reverse. If you put your ear right next to the sensor (those little buttons on the bumper) you should hear a "tick, tick tick" from them. My hunch is that you'll find one that is not like the others.

It may be a little unnerving to have your head behind a car that's in reverse. Be sure you really trust your friend..

 

[Joe in NY]

Thanks Mike, I'll check the sensors and let you know.

 

[Joe in NY]

Mike,

I finally got around checking the sensors. Of course when I did they were working right and the beeper inside the car came on as I put my ear to them. However, I heard no clicking noise from the sensors themselves. It's still very hit-or-miss when they work with it being more "miss" than "hit."

One clarification though, the car was in reverse before I went to the back. Would the "clicking" only occur for a short period after putting the car in reverse as a quick diagnostic and then not make a noise when in the operating mode?

 

[tixer]

My understanding, is that they'll "tick" for the entire time that they are active.

I have to stress that I've never had to troubleshoot these things in person, but a buddy of mine had them on a different Ford, and that was part of the procedure. In his case, he said they were pretty clearly audible with his ear right up next to 'em.

I'm relatively sure that in the scenario I read up on, the "tick" is the result of the sensor emitting the radar(?) signal itself.

 

[Joe in NY]

I'll try again but I didn't hear anything at all. Maybe try the screwdriver in the ear trick.

 

[driller]

I don't recall the year/model change but the older sensors used sonar and the newer ones use radar. The "tick" test tells me that's sonar as I remember from using sonar measuring instruments from years ago.

I also believe the little round buttons were the sonar based systems and the radar based system has sensors behind the bumper cover not visible from the exterior.

 

[tixer]

That makes a lot of sense.

I didn't know that they'd changed the technologies. Thanks for that.

 

[Lvnmarks]

I wonder why they started with sonar...it's a terrible system out of the water.