[rotarypower101]

I need a powered auxiliary line to run a accessory to avoid vampiric drain.

Where is the easiest closest location to use as a power on signal wire in a 2008 e92 near the battery?

Has anyone done something similar and could advise please?

Is there anything in the area of the rear passenger/right side near the battery that is only active when the car is powered up?

The hope being I could use that as a signal to power a relay and pass current needed through a relay.

[Andystobbs]

Supply line at PDC is only live when T15 relay is active.

[rotarypower101]

Originally Posted by Andystobbs

Supply line at PDC is only live when T15 relay is active.

I will check it out, thank You!

Would you happen to know if the PDC is a +12Vdc line, and if from experience/understanding if a small low amperage relay could be driven safely off from the PDC?

Reading through many threads, and there have not been any solid clear answers where people are sourcing a switched power tap in that area around the battery specifically. trunk area in general.

So, very grateful for the reply above!

[Andystobbs]

Yes all control modules are 12v supply. You could energise a relay coil as per your idea without a worry. Just ensure that you connect the relay the correct way around so that the diode inside forces the back emf to go to the ground side when the line is switched off and the field in the coil collapses. You'd better verify the presence of the diode via the pictogram on the relay but they're practically universal. If in doubt add a diode in.

Stuff like lighting wires is more of a nuisance because of the PWM of the voltage.

[rotarypower101]

Originally Posted by Andystobbs

Yes all control modules are 12v supply. You could energise a relay coil as per your idea without a worry. Just ensure that you connect the relay the correct way around so that the diode inside forces the back emf to go to the ground side when the line is switched off and the field in the coil collapses. You'd better verify the presence of the diode via the pictogram on the relay but they're practically universal. If in doubt add a diode in.

Stuff like lighting wires is more of a nuisance because of the PWM of the voltage.

May I ask another partially related question in reference to the PDC, as it seems like this might be a topic you possibly would either be familiar with or have come across in reference to the PDC system.

I commonly tow a trailer requiring accurate positioning in tight areas while backing up, the PDC system in the rear of the vehicle incessantly/infuriatingly goes off when backing up into technical situations because of the close proximity of the trailer/hitch, blaring, and not adding to the sometimes difficult, concentration intensive task of driving a trailer in reverse...

Is there possibly a good way or technique to defeat/disable the rear PDC sensors only when a trailer plug is active, without triggering unintended issues like error codes?

I believe they made a PDC disable button for one of the BMW models for the European market, but the US domestic market and specifically the E92 didn't come with nor will facilitate this switch, if what I read was accurate.

Possible you know a bit about that topic, assuming your knowledge of the PDC system extends that far and to a niche application like that?

[Andystobbs]

Not knowing how your trailer lighting is wired doesn't help but I'm going to assume bypass relay.

If you bought and installed the AHM module for handling trailer lighting this would solve your problem once coded. The AnnHanger Module is the OEM trailer module and is completely integrated into the car. When it sees a resistance across any two lighting circuits and ground it decides that a trailer is plugged in and automatically deactivates rear PDC.

Changes to behaviour are also made in the DSC when towing so that it responds according to a car and trailer setup for stability control.