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BMW Switchgear wiring

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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:

--- Quote from: tngarren on October 08, 2025, 01:07:01 AM ---@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.

--- End quote ---

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:

--- Quote from: tngarren on October 08, 2025, 01:09:17 AM ---@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?

--- End quote ---

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.

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