Wisconsin Joe

I got an 05 CTT about two months ago.

The rear park assist didn't work when I got it. It just gives the "long beep" and outside red lights that are "failure" mode, according to the manual.

The front PA works just fine.

I can feel the "clicks" on the front sensors.
But nothing on the back at all.

Followed the writeup to pull the back bumper cover off, and took a look.

There was a fair amount of dirt/gravel/mud on the outer parts, including caked around the outer sensors. The rubber cover on the side of the senors that were caked in mud seems "squishy" - soft and loose. It seems firm and solidly attached on the other sensors.
Pulled the sensors and checked the connectors, all seemed ok.

I have continuity through the wiring harness in the bumper.
I have ground and 12 volts from the ground and positive on the main plug.

Plugged everything back in, and still no "clicks" from any of the rear sensors. Still have the "failure mode" lights and beeps.

Now what?

I'd really rather not just start throwing new sensors in without knowing what's wrong.

Is there any way of testing the sensors? Can I just put 12 volts to the power connections (outer 2 on three prong plug on sensor, right?)? Will that make it "Click" if it's good?

I looked at pulling the front bumper off and switching "known good" sensors to the back and "questionable" ones to the front (one at a time), but getting the front bumper off, or even getting access to one of the sensors is a pretty big job.
Is there any easy way to access at least one of the front sensors?

I searched around on here and on google, but for the most part they just talk about sensors 'clicking' and replacing them.

Any and all suggestions are appreciated.

Orantes

What you describe is exactly the same result as when you fully disconnect the main loom plug at the bumper (left hand side where wiring comes out of body), Have you cleaned up the main plug connection? It can get dirty. For reference, I have a 2004 S.

Jonathon Rolstin

Use durametric and it will tell you exactly which ones are bad, then you can replace them for something like $40 each I think!

Wisconsin Joe

Yes. I pulled apart and cleaned up all the plug connections.

None of them looked bad, at least on the inside. All the seals looked good, the contacts were clean and there wasn't any dirt or moisture that got past the seals.

I'm wondering if the 2 bad sensors are damaged to the point that they are shutting down the entire system (shorting it out or sending invalid signals or something).

If I pull a sensor off, will it shut down the whole thing? Or will "no signal" from a disconnected sensor just be like it wasn't detecting anything?