I have a vehicle which I have upgraded the AV electronics from a newer model (infiniti G37). To do this, I created an adapter harness that effectively moves the wiring to the new locations. The wiring harness includes a CAN BUS pair of wires. The adapter harness is approximately 7 inches in length. At the time of doing this, I did not have enough knowledge of CAN bus to know that I needed twisted pair.

I developed an issue while driving, where the one component that uses the CAN BUS wiring became completely unresponsive (Climate Control). After shutting the car off for a few hours, the system became responsive again. this has happened a few times now, but is inconsistent as to when it occurs.

It's possible that I just have a loose wire, and will be double checking that, but given that the AV unit's internal system diagnostic software won't let me select the Climate Control system to diagnose when the issue occurs makes me think that I have an issue with the CAN BUS. Once the system is back to working, the diagnostics of the climate control system work fine.

My question... would not having twisted pair in the for the adapter cause enough error to cause the system to become this unstable?

I do plan to address the issue immediately but mostly wanted to understand the effects.

  • 1
    \$\begingroup\$ It makes it less tolerant to noise. \$\endgroup\$
    – DKNguyen
    Jan 13 '20 at 21:47
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    \$\begingroup\$ A car is a very electrically-noisy environment, \$\endgroup\$
    – rdtsc
    Jan 13 '20 at 21:48
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    \$\begingroup\$ Even in very noisy environment 7" of untwisted wire should not make much difference. More important would be the quality of the extra connectors and wire impedance matching, as both introduce reflections. In any case, I would look for bad connection first. \$\endgroup\$
    – Maple
    Jan 14 '20 at 0:20
  • \$\begingroup\$ Thanks. I'll be modifying the wiring to be compliant. While there, I'll double connectors. \$\endgroup\$
    – Andrew S
    Jan 14 '20 at 21:25

Just came back to answer this: * twisting seemed to reduce the number of errors the system was reporting. But it didn't solve the disconnecting issue. * found that the connector didn't quite plug into the AV unit tight enough, and that one of the can bus wires had a little too much play in the connector. The connector is probably just a bit different than the OEM allowing for some "wiggle".

Either way, thanks for the discussion and it certainly helped/made a difference.


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