What do the electrical pins in the OBD2 connector cover do? I just got a diagnostic scan module that outputs information by wi-fi to my iPhone. I want to keep it plugged in although it seems to have power with the ignition off. I don't want to defeat the cover pins function if they have one.

 

I too tried to solve this mystery.

So far I came up with no rational explanation. I measured the Mini's quiescent current and found it to be identical with the cover closed or open. I drove the Mini with it open and have no crash and burn.

I think it is one of the let's make the provision design thing just in case. I infer it is there to signal the modules on the bus - smarten up, guys, we have visitor and may be DEQ.

 

Just a side note to leaving one of those transmitters in the obd2 port. I did it for a while and constantly found myself kicking the transmitter when I went from clutch to dead pedal. YMMV

 

I use an OBD2 extension cable and mount the scanner on the underside of the steering wheel. The cable still allows connection to the port for auxiliary connections or emissions testing.

 

I have a HUD that uses the OBD2 port. I took the hinged cover off. Mine has a resistor on it.

 

The pins on my cover (1,2, & 9) are connected together and cause my wireless scan reader's power light to come on. I have an in-line switch extension cable that let me move the scanner out of the way but with the cover installed, it activates the power light but none of the other lights. I'm still torn about whether or not to install the cover. Does anyone know where the wire diagram for the OBD 2 connector can be found? I can't find it in my Bentley. Mine's an 03 Cooper S.