You can find these adaptors on eBay by searching for usb (kkl, 409.2, OBDII, OBD2) and bmw (OBD, OBD2, OBDII) (adapter, 20 16). The 16 to 20 pin connects 17 and 20 together and feeds them into the OBD2 convertor. So the USB adaptor does the conversion to OBD2 KL protocol. This has a wire inside that shorts pins 17 and 20, and connects them to 7. Since you will probably want the full suite of modules INPA software offers, you need a £6 BMW to OBD2 adaptor. Handily both K lines can be shorted to get a simple OBD2 K USB adaptor to work.
If you want the ABS, Airbag or anything else, you need the 12V, GND, and both K lines found on the round connector. If you want to talk to the engine and gearbox you only need the 12V, GND and K line found on the 16 pin connector.
If you don't have the 2nd K line, you can tap into it behind the instrument cluster if you wish. Your car may differ on the 16 pin connector. The car in this case is a 1999 and has both the 20 pin and 16 pin OBD diagnostics. One for the engine and Gearbox, the other for everything else. It's called the KKL since there are 2 K lines. This may not apply to some early E36 and ///M E36 cars, where older modules with low computing power appear to need the L line for Rx data. With the ignition on, the L Line is not needed, since the modules are already awake. As such the BMW is not dierctly compatible with RS232, either in baud or signalling levels, and could damage your PC's RS232 port if directly connected. L line is some sort of RTS/DTS line that wakes up the modules on older cars.
Bmw inpa guide serial#
The K line is a bi-directional serial bus with a 10.4kbaud data rate. Here's how I did it using cheap USB interfaces.īMW uses a KKL system on the 90's cars. It lets me read fault codes, live engine statistics on a per cylinder basis and reset engine adaptations after repairs.