PDC Rear off

[apw2607]

Originally Posted by wdc330i

Can't you just deselect PDC in Idrive?

No ... alas. Life would be easier if you could !!

So ... I spoke to soon. It turns out that with everything connected, when I use the left signal indicator, with the connection made to the hitch electrical outlet, the blinkers blink really quickly.

Odd ... they must be somehow on the same circuit. I'm going to investigate further and report back. Sure I can figure it out.

[xDrive35d]

apw - You may want to open up that plug that came with the light you bought. Or see if there was a schematic with it. Sounds like they may have wired it to "blink" the light with either turn signal?

[apw2607]

Ok. All working now.

Heres the scoop. If you are using the adapter plug that came with the hitch like I was, you must connect to both the left/right blinkers and the brake light as they share a common circuit. If you just use the brake light, one of the circuits becomes open and thus causes the issue I was having. Ideally, you also need to connect the taillight too otherwise you;ll get a warning message on idrive

So .... simply buy one of these.

And some resistors. I'm experimenting with different values right now, but if you goto radio shack, you can buy 4 x 10 ohm, 10w resistor and 4 x 8 ohm, 20 W resistors to work for each circuit as described below. The resistors will get warm-ish, but thats normal. I've minimized this based on the resistances and configurations. Gonna try some higher values resistances, and lower wattages, and see what happens. BMW might have got tricky, and having higher resistances may mean it doesn't see the load ..... we'll see. I knew my degree in electrical engineering would come in handy one day. Never used any of this since I got the bloody thing ;-)


4-Pole Trailer End Connector 18004 : Trailer hitch bike rack and trailer hitches - etrailer.com

** Revised values after testing **

White is ground

Green is Right Turn and Stop/Brake (add 2, 10 ohm, 10W resistors in series)

Yellow is Left Turn and Stop/brake (add 2, 10 ohm, 10W resistors in series)

Brown is Tail lights (2 x 8 ohm, 20W in parallel connected in series to 2 x 8 ohm, 20W in parallel)

I'm so happy not having that rear PDC beeping sound whenever i goto reverse now, but still have the use of Front PDC and rear view camera.

[JCL]

Interesting thread. I recall the same discussion about an E53 on this board several years ago, and the fix for the PDC beeping with the bike rack in that case was a 7 pin to 4 pin adaptor. I can't recall if that model required the resistors or not, I didn't think it did. I am sure the E70 wiring is different enough that apw's solution, above, is the way to go. My bikes go on the roof, so I never tried this myself.

It occurs to me that one of the commercially available 7 pin to 4 pin lit adaptors may provide sufficient load to turn off the PDC. This one below is powered from the tail lights. It is $14 at trailer supply outlets. Even if the LED isn't enough load to turn off the PDC, adding a resistor inside this model might be neater than an external load.

[apw2607]

Thanks for that. The above adapter uses just the tailight function for its night glow effect. If you plugged that in, although the PDC may switch off (not sure if just the LEDS will provide sufficient load) but the idrive and center display will definitely report open circuit (or lights out) on brake and left/right blinkers warnings for your trailer ....

BMW designed this car to be smart. Sometimes its just too smart !!