2011 BMW intermittent K-CAN codes
This BMW sets intermittent K-CAN codes in about 10 modules and in my first capture, CH C shows the green wire K-CAN signal is erratically toggling above ground at the HVAC module and CH D is the yel K-CAN wire at the HVAC. The same K-CAN signals are at the radio.
There are no signs of any water in the trunk but there is a lot of white corrosion in the wire harness under the driver side carpet, caused by water intrusion.
In the second capture,
CH A is the grn K-CAN wire at the radio
CH B is the yel K-CAN wire at the radio
CH C is the grn K-CAN wire at the HVAC
CH D is the yel K-CAN wire at the HVAC
I don't think that the last capture is a good K-CAN signal
Someone gave me a good K-CAN waveform and in the last capture, the lower voltage should not be wavy, the lower voltage should be flat at 884mv.
The last capture does not look that bad to me... Here is one description of K-CAN: us.autologic.com/news/bmw-instr… "K-CAN is a 2-wire system; one wire is K-CAN High, and the other is K-CAN Low. • Use oscilloscope to diagnose K-CAN High and Low patterns. High and Low square wave should mirror each other. A volt meter is only a quick check and not a definitive
Ray, I think you should look at SI B61 18 14. This is a common problem and would be a good place to start. If you can't find it I can send it to you tomorrow. Good Luck, MIke
Do you refer to this SI? static.nhtsa.gov/odi/tsbs/2014….pdf It's for K-CAN2, not K-CAN... Is there a similar one for K-CAN?
I think its important to mention, to prevent confusion among those that aren't well experienced with BMW. "K CAN" is a CAN Bus only in name, it doesn't follow the standard rules of CAN Bus everyone is generally familiar with. It is essentially 2 single wire K line bus' in which one has been inverted. There is no standard or even documentation of terminating resistors and the value can be 800ohms
Hi Dmitriy, That bulletin only applies if the faults are K-Bus2 related. I should have paid more attention to the details of the post! Thanks for correcting me! Mike
I think its important to mention, to prevent confusion among those that aren't well experienced with BMW. "K CAN" is a CAN Bus only in name, it doesn't follow the standard rules of CAN Bus everyone is generally familiar with. It is essentially 2 single wire K line bus' in which one has been inverted. There is no standard or even documentation of terminating resistors and the value can be 800ohms