wrathalanche

Hey guys, looking for a break down of the beeps.

My car came with what I thought were after market PDC sensors, since they were black and the car is silver grey. There was no manual or anything inlcuded with the car that went with the sensors

But today I dug into the boot and investigated the harness, and it turns out it IS oem BMW sensors, as the harness went into a little BMW "HELBAKO" box. My car has no PDC option on the iDrive, so that further confirms that they were a retrofit job.

Anyway, I understand the audio signals as far as the distance control goes- constant beeping in close proximity, one long beep at 30cm or so. However, at other times, like for example during the whole parking process, it seems to beep in quite a few patterns, and it isn't until I'm lined up with the car behind and closing in on it to end the park, that the simple proximity parking pattern of beeps starts.

Can anyone explain what the signal patterns mean, ie- are they telling me an object is at an angle to me or something?

Also, any advice on spray painting the sensors would be pretty helpful.
Cheers,
Dave.

AlwynMike

It could well be that your sensors are picking up objects at the side of your car, as the beam pattern does extend beyond the width of the car, and this can bring a sensor in, particularly if you are parking between other cars.

If it is a genuine BMW kit, then you should be able to get the car programmed to display the sensors on iDrive, but this may throw up an error because you have no front sensors fitted, and it will look for those. It is probably not cost effective to do this either.

It is not unknown for the sensors to pick up the road surface when for example, you are reversing out of your drive and the car is pointing rear downwards. This happens to me as I'm reversing out of my parents' drive - it picks up the road, then the bush at the side of the drive (with the front sensors) and then the opposite pavement.

I haven't done a check to see distances for each bleep sequence.

I haven't done any spraying, but I understand (from browsing eBay!!) that you can go into Halfords with your paint code and they will mix up an aerosol can for you. Take the sensors out, prime with plastic primer and then with the topcoat. Don't lay it on thick though!! You can get to one or two of the sensors without taking the bumper off, but not the others. Removing the bumper is a pretty easy job though, particularly if you don't have rear mudflaps.

Have a look on Witter-towbars.co.uk for the towbar fitting instructions, and it will tell you there how to remove the bumper.

Mike

Rudy

I'm thinking that your car had the BMW aftermarket PDC system (shown in the accessories catalog -- see .pdf page 22 of this link) which I believe only works on the rear and does not interface with the central information display.

As far as the beeps go, Mike is correct that as you approach objects you will get some various signals but as you continue to approach, the closest one will start to give a steadier tone. All this is assuming that the aftermarket version works just like the factory version...

wrathalanche

Cheers guys,

I'm not really looking to get my sensors hooked up to the display or anything anyway- just figured that since the option wasn't there in the iDrive, I could be fairly certain they weren't in the original spec (had the fact that they were the wrong colour not been enough!).

Having trouble opeing your pdf Rudy just now at work but will have a look when I get back home to try confirm if it's that set I have.

As for the cause of the beeps well you may be onto something Mike, I think I have noticed it most when reversing off the driveway outside my house. Its not really a drive way, but 2 concrete strips through the grass that leads to my gate that I'm sometimes forced to park on. I have to bump my car up and down the curb when going on and off, and what might be happening is when I get my 2 back wheels off, the sensors may be picking up the ground. I haven't thought about it too hard up till now, but I'll try keep a record of exactly what kind of patterns it makes and when in the future and can come back with maybe some answers.

As for spraying them, yes I'll be using Halfords for my spray. Used to work there until last year so I'll be popping in and asking my old boss if I can mix up my paint myself, at least that way I know its done right, and can only blame myself it its crap.
But more specifically I had read into problems with the likes of metallic paints causing problems when coating the sensors, especially sivlers, which is what I need. Since I'm mixing the paint myself I could leave out the metallic base or pearlescent base additives that sometimes go into the paints without effecting the overall colour, but I'm not sure exactly how metallic the colour ingredients themselves are. Just wondering if anyone had experience spraying them with off the shelf silver paints, and if there were any problems. On some other sites they say that I shouldn't spray over the centres of the sensor, so I'm a bit confused.

Might even try it out without the primer first, so that its easier to strip them once I know if they work or not, and if they do, them strip them, prime them and coat anew. Plan?

AlwynMike

The way I THINK that these things work is that the surface we see is the actual area that vibrates ultrasonically, and then picks up any echoes that return. i.e. it is like a loudspeaker cone, with a microphone in the middle. If this moving membrane were covered in, the sound waves wouldn't penetrate the cover and would be useless. This is one of the reasons that they don't like being power-washed!!

The addition of a couple of layers or so of paint shouldn't affect them too much - a decrease in range probably, but you would still get protection closer to the car, which is where you want it. As they work using sound, rather than radio waves, the silver particles shouldn't make any difference, as the paint itself would be vibrating too (as opposed to radio waves going through it).

Apologies if you know all this already.

Mike

wrathalanche

Ah, good call Mike. Never thought of them as literal sound waves, acting differently from radio waves. Ok, well once I can guarantee a full day of good weather (a very difficult thing to achieve in Scotland) I'll get to it. As usual, any disasters- I'll be sure to share