Cannot hear parking sensors after head unit upgrade

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Cannot hear parking sensors after head unit upgrade

Post by JDMils » Thu Jul 19, 2018 4:23 am

So my daughter replaced her factory head unit with an after-market head unit and now she cannot hear the rear parking sensor beeps. She added a steering wheel adapter so that she can use the steering controls and that works gr8.

My question is: How do the parking sensors wire into the original OEM head unit? She is using the same wiring loom as the original so shouldn't the parking sensors still work?

Car is 2007 BROWN B.M.W. Hatch 120i E87.

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Re: Cannot hear parking sensors after head unit upgrade

Post by Nottsknots » Thu Jul 19, 2018 5:39 am

I assume the PDC sounds came from the HU speakers, rather than separate speakers at the rear/front? Which HU did she replace, and do you know the production month - they changed after September 2007.

The PDC module communicates with the HU via CANBUS, so it does not "wire into the HU" as such; if the HU cant interpret the CANBUS signals and generate its own tone, then it wont work.

Sometimes (often) when folks change between BMW HU's they loose the beeps, but the BMW HU's just need to be coded to recognise the CANBUS signal. As she has an after-market HU, it may not even have that capability. Which HU has she got now? If it cant be programmed, then it may be possible to add the separate speaker like the older (pre September) models - not heard of anyone doing it, but it might (possibly, maybe, perhaps) be possible :?:
E87 118d, stock, plus PDC control unit drain, Parrot, debadged, Mothercare baby shades (but no babies), and occassionally a good layer of wax. Instantly forgettable, and thats the way I like it.

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