BMW Switchgear wiring

[tngarren]

2021 R18 but topic would generally apply to all CAN bus BMWs. 

I had to replace the plastic cruise control controls on the left-hand switchgear.  Like most of my work, I fixed one thing and broke another.  Now the cruise control works, however, the horn and turn signals stopped working.  The other functions on the switchgear work - cruise control, flashers, high beam, menu, aux lights. 

All the functions run off 3 CAN bus wires - 12V, CAN L, and CAN H.  They are getting 12V, 7V, 7V to ground with ignition on.  So, I am thinking the problem is on the switchgear.

I have disconnected the battery to reset the bike control units but no help. 

Is there a way to read the CAN bus data to see if the horn and turn signal buttons are sending any data?

Any other diagnostic advice is appreciated.

Pic attached.  Four circled buttons are left, cancel, right.  Bottom is horn.

https://imgur.com/a/XSyNCBs

[schuppi]

Hello

This is what the GS911 is designed for.
Here you can read the real-time data in the Body Controller Lite XBCL and check its functionality.

[tngarren]

I am sorry, I do not understand.  I can see some real time values like temperature and horn on, etc. with my GS-911. However, I cannot sniff the real time CAN buss data packets.

[schuppi]

# I cannot sniff the real time CAN buss data packets #

Sorry,
This is not possible
other devices would be required.

[botus]

2021 R18 but topic would generally apply to all CAN bus BMWs. 

I had to replace the plastic cruise control controls on the left-hand switchgear.  Like most of my work, I fixed one thing and broke another.  Now the cruise control works, however, the horn and turn signals stopped working.  The other functions on the switchgear work - cruise control, flashers, high beam, menu, aux lights. 

All the functions run off 3 CAN bus wires - 12V, CAN L, and CAN H.  They are getting 12V, 7V, 7V to ground with ignition on.  So, I am thinking the problem is on the switchgear.

I have disconnected the battery to reset the bike control units but no help. 

Is there a way to read the CAN bus data to see if the horn and turn signal buttons are sending any data?

Any other diagnostic advice is appreciated.

Pic attached.  Four circled buttons are left, cancel, right.  Bottom is horn.

https://imgur.com/a/XSyNCBs

did you dismantle the switch or swap the entire thing ?

if you swapped it out - is the new one OK - everything plugged in - maybe plug in the old one and see where you are - no need to mount it to the bike

these things are strange and sometimes multiple versions exist - dependant upon the toys on a given bike -
on my GS they all behave differently but you'd think they were all compatible parts - they are not - they don't just switch - they use weird beard different resistances and magically different wires connected up inside to the multiplug

you must match the exact same part number

example

01    Combination switch left       1          61319467929    (says cruise)
01    Combination switch left       1          61319467931    



https://www.realoem.com/bmw/en/showparts?id=0L11-EUR-04-2021-K34-BMW-R_18_0L11,_0L13_&diagId=61_6744






 

[karlh]

Your voltages suggest the communication from the switch cluster is via a LIN bus, not CAN.  CAN voltages usually top out at around 3.5 volts, while LIN voltages are higher.

[tngarren]

@botus Thank you. It is not a new switchgear.  I dismantled the switchgear housing and replaced the plastic thumb controls for cruise on/off and set/resume. Cruise control works fine now.  However, the horn and turn signals stopped working. 

[tngarren]

@carlh Thank you.  LIN bus is new to me. I will need to get smart on that.  Any idea why 3 wires - 12v, 7v, and 7v would be going to the left-hand switchgear?

[botus]

@botus Thank you. It is not a new switchgear.  I dismantled the switchgear housing and replaced the plastic thumb controls for cruise on/off and set/resume. Cruise control works fine now.  However, the horn and turn signals stopped working.

so all the wiring and all the switches are original and should be 100% normal - so either didn't re connect or now something is broken

double check the internet - were some of the R18s switchgear's faulty from birth - I seem to recollect hearing that

[karlh]

@carlh Thank you.  LIN bus is new to me. I will need to get smart on that.  Any idea why 3 wires - 12v, 7v, and 7v would be going to the left-hand switchgear?

Your switch cluster probably contains a small microprocessor that communicates switch actions to a central control unit.  Just like CAN, this simplifies wiring by only requiring the three wires you described instead of individual wires for each switch.

[tngarren]

@karlh Thank you. That is good to know.  Since other controls on the switch gear are working - cruise control, flashers, high beam, I am thinking the problem must be on the switchgear itself and not the wiring.  Your thoughts?

[tngarren]

@botus. Thank you.  I am hopeful the problem is the switchgear since I just ordered a replacement off eBay for $360USD.

[tngarren]

@kcarlh  Correction.  Regarding the 3 wires going to the left-hand switchgear. On is reading 12V, one is 7V, and one is a ground. According to AI, the LIN bus data wire can read 7V on a multimeter because it is switching between 0V and 12V rapidly. 

I initially misread the ground as 7V but I failed to notice the mV.

[karlh]

That would definately be a LIN bus.

[tngarren]

I replaced the left-hand switchgear.  All good now.