How to use/switch/connect to K-Line or Dcan pin 7&8? I have one of those K+DCAN USB cables and I am confused about how to switch the modes of it. Here are good tips i found, of the switch-mode k+dcan usb cable user manual. All i’ve collected just for education.
About the switch-mode K+DCAN interface –
I assume the reasons being that on DCAN cars one pin is used for a ethernet connection and the other to the K data line – on K line cars, both pins are connected to K data lines and that creating a switch mode circuit would cost more than the interface is worth. The 2 most sensible options are both hardware-related:-
- Use an adapter (such as the one sold by One Stop electronics) which internally bridges pins 7 & 8 or,
- Mount a small switch on the OBD plug end of your adapter, which can bridge (for K line) or separate (for DCAN) the connection between pins 7 & 8.
Tip: the normal dcan cable vs. switch-mode k+dcan cable:
– So you have to physically connect (K-Line) or disconnect (DCAN) pin 7&8?
– Yes, I think connection by soldering is a bad option as it limits the usefulness of the interface, I have an adapter but consider a switch to be a better option.
– Is there anything else to do for switching from K-Line to DCAN then disconnecting pin 7&8? Unfortunately I don’t have a DCAN model available.
– As soon as you connect the interface to the car and your computer, run DCAN.exe to configure the comms rate. I have only used my K+DCAN interface with DCAN cars.
– Is it necessary to do so every time I want to use DCAN or is the interface staying in DCAN mode once I ran DCAN.exe?
– You only need to run it when you are switching between modes. If you run it the first time you connect to a DCAN car, your computer will retain the settings.
– How do I switch back to K-Line? Just by connecting the two pins or is further action on the computer required?
– Earlier e39 had both the OBD port in the cabin and the round 20 pin connector under the hood.
The OBD port only allowed access to limited modules, I think only the DME in fact.
I always switch my K+D CAN adapter between K and D CAN protocols as I need to, depending on the car that I’m connecting to.
I use the DOS version of the DCAN utility. As mentioned if you only use the adapter on the e39, run the utility once and set the adapter to K CAN and leave it at that.
In fact thinking about it I use the same adapter for INPA, DIS and ISID.
With these K DCAN cables there are two subtle different versions, one with pin 8 enabled, one with it disabled. The one with it disabled is ideal for e90 newer than 03/07 & that era, these leads often come with a black adapter to re-enable the pin 8 (by just tying it to pin 9) so it will also be suitable for e46/e39/e63 etc. The ones with pin 8 active are just older versions of the cable. Worst cast scenario you just need to modify the cable & stuck a switch on it to toggle pin 8 on/off as needed.
Finally there are a lot of rubbish adapter cables out there. Finding a good one can be tricky.
– I have a 2003 E39 so there is no OBD1 anymore. How do you switch the modes physically? Do you use such a adapter to connect Pin 7&8?
– If you don‘t plan to use the cable on any cars that have DCAN(2007+) then you can pop open the case and solder a jumper between them. When you do this the DCAN functionality will no longer work though.
Tags: BMW Diagnostic Tool BMW INPA K+CAN Dcan Cable