Guide: Four-Position Switch – K+DCAN USB Interface OBD2 Cable for BMW

Guide: 4-position switch – K+DCAN USB Interface OBD2 Cable for BMW

This guide applies to (K+DCAN USB Interface OBD2 with 4-position switch) for diagnostics with, for example, INPA, NCS Expert, ISTA/D, and ISTA/P.

Quick Overview

Position 1: Pin 7 (K-Line)
Position 2: Pin 7 + 8 (bridged – Dual CAN/K-Line variants)
Position 3: Pin 8 (alternative K-Line, e.g., certain E65/E66 modules)
Position 4: Pin 1 (special/older modules; sometimes in combination with 7)

How does the switch work?

BMW uses different communication lines via OBD2 depending on the model year and platform. The switch positions control which pins are active in the OBD2 dongle so that the cable can communicate with the correct module(s).

Position	Active pins	When is it used?	Comment
1 – K-Line	Pin 7	Older BMW (E36, E38, E39, E46, E53) and early E-series	Standard K-Line. Starting position for cars up to approx. 2006.
2 – 7+8 bridged	Pin 7 + 8	Newer E-series (E60/E61/E63/E64, E87/E81/E82/E88, E90–E93, E70/E71, MINI R56/R57)	Common for approx. 2007–2013. Provides contact with modules using both lines.
3 – Pin 8	Pin 8	Specific platforms/modules (e.g., certain E65/E66)	Use if Position 1/2 does not provide contact, but the car/module requires pin 8.
4 – Pin 1 (special)	Pin 1 (sometimes in combination with Pin 7)	Older special modules/comfort systems	Rare. Test only if module requires it or for documented need.

Recommended positions per model series

Model Series	Year (approx.)	Position	Note
E36, E38, E39, E46, E53	–2006	Position 1	K-Line
E60/E61/E63/E64 (early)	2003–2006/07	Position 1	K-Line, try Position 2 if a specific module is missing
E60/E61, E87/E81/E82/E88, E90/E91/E92/E93, E70/E71	2007–2013	Position 2	7+8 bridged
E65/E66	2002–2008	Position 3	Pin 8 is used by some modules
MINI R56/R57	2007–2013	Position 2	Dual CAN / bridge 7+8

Installation (Windows)

Connect the cable to the computer (not the car yet).
Install the correct driver: FTDI (most common) or CH340 depending on the chip.
Open Device Manager → note the COM port assigned to the cable.
Set the same COM port in your software (INPA/NCS/ISTA). Avoid high port numbers – COM1–COM4 recommended.

Step-by-step usage

Select the switch position according to the tables above (do this before connecting to the car).
Connect the OBD2 connector to the car.
Turn the ignition to position II (dash lights on, do not start the engine).
Start the software (INPA/ISTA). Check that battery/ignition is indicated correctly.
If no connection – switch to the next position and try again.

Common problems & solutions

Problem	Cause	Solution
INPA shows “IFH-0009: No response”	Incorrect switch position / incorrect pin configuration	Try the next position (1 → 2 → 3 → 4). Also check the selected model in the software.
Program cannot find the cable	Wrong COM port or driver	Set the same COM in the program as in Device Manager. Install the correct driver.
Some modules respond, others do not	Different modules use different pins	Change position (often 1 ↔ 2). For E65/E66 – try position 3.
Unstable connection/disconnections	USB extension or low power	Use the computer's USB port directly. Avoid hubs/extenders.

Technical reference (OBD2 pins)

Pin 1: extra/special K-Line (older modules)
Pin 4 & 5: ground
Pin 6 & 14: CAN High/Low (D-CAN)
Pin 7: K-Line
Pin 8: alternative K-Line/line for certain modules/platforms
Pin 16: +12 V power supply

Safety notices

Do not change the switch position while the cable is connected to the car's OBD2 socket.
During coding/programming: use a stable power supply and avoid turning off the ignition.
Always back up module data when the software offers it.