pdc control unit..

[road warrior]

im trying to sort my non working pdc, having established its the control unit at fault i bought a secondhand one the first one made a buzzing noise the moment i put it into reverse but not close to anything, no vibrations from any sensors,
now. realoem says it should be 66216914108
but i found 66216942675 in the boot of course not working .. doh..
i acquired an 66216900270 which i was assured was fine, but that makes a loud noise from the dashboard when i put it reverse and lights up
carly , so - thoughts please ?

[Sideways Steve]

do you mean when you put it in reverse it makes a long constant tone ? if so its telling you that one or more of the sensors are knackered.

[road warrior]

yes it does, i had assumed the control unit was buggered, the serial number doesnt match up with the bmw database either but then..

[road warrior]

so to recap, i have tried touching them testing for a noise or vibration and had reasoned it was unlikely that all 4 sensors were buggered, but your saying it buzzes when even one is buggered ? if so how on earth do i work out which one without taking them out ? are they accessed through the boot or underneath ?

[Sideways Steve]

The only way to truely determine if the sensors themselves are knackered is to use the propoer BMW diagniostic software as it will override the cutoffs on them and show you real time readings from each sensor so you can see which ones detect and which ones dont.

ISTA-D is best I find but DIS and INPA are also able to do it.

To give you an idea, I had to replace all 4 of mine even though they all clicked happily when switched on and I didn't have the long tone but the sensors were still faulty.

You have to ensure you buy genuine sensors with the correct part number to match the rest if your only changing one or two. if your changing them all then I think you could get away with aftermarket ones. This is because for some reason the E85 PDC system seems to be quite fussy about what sensors you use. I had one known faulty one on the left which was causing the long tone initially. I changed it for a brand new aftermarket one and that solved the long tone issue but I still got no beeping when reversing at all. I then changed the new one for a second hand genuine one and the system started to partially work but the middle sensors seemed to not give any readings.

Only when I changed all 4 for a set of genuine second hand ones did everything start working properly again.

To remove them you can do the two outer ones by just taking the rear lights out but they tend to get stuck in the holders which are lightly glued to the bumper so your best bet is to whip the rear bumper skin off so you can remove them all easily without breaking the holders off the bumper. if you do break the holders off though they can easily be glued back on so not to worry but again having the bumper off to do this is far easier and you wont cut your hands to shreds!

[Sideways Steve]

Oh and for the record, you can get second hand E39 sensors on ebay cheap enough as they are the same type. I got my full set of second hand E39 sensors for £40 then just re colour coded them to match my car which was much easier than you would think.

[road warrior]

thank you - will look into it

[mac27040]

did you sort out the faulty sensor, i can run laptop on it to see which one is faulty

[mjennings23]

You have to ensure you buy genuine sensors with the correct part number to match the rest if your only changing one or two. if your changing them all then I think you could get away with aftermarket ones. This is because for some reason the E85 PDC system seems to be quite fussy about what sensors you use. I had one known faulty one on the left which was causing the long tone initially. I changed it for a brand new aftermarket one and that solved the long tone issue but I still got no beeping when reversing at all. I then changed the new one for a second hand genuine one and the system started to partially work but the middle sensors seemed to not give any readings.

That seems to be exactly what has happened with mine, albeit I haven't got round to replacing all 4 yet. I've ordered a set and a PDC module off ebay so can try as required, keep the parts that fix it and send the unneeded bits back.

Finally gave me the incentive to get it sorted!

[mjennings23]

Well for my resolution, seems the PDC module was buggered. Strange as all the sensors were outputting to it and could be read via ISTA, but a new module has sorted it and now I have beeps!