Comma AI self driver assistant

[Shmoe]

CAN Bus Disconnected: Likely Faulty Cable means exactly that, we have a problem with the USB cables. Let's look at your configs below:


This should work, so one of these cables or the adapter must be bad.


This will not work for sure. Two long ODBC cables is a problem (known from experience)

Cruise Fault: Restart car is a different message, this means the Ford Radar has an error code in it. Usually this happens during hard rain, but it is possible the comma did something to cause it to fault.



I have never heard of USB 4.0, that must be new, and I'm not sure how it will work with comma.

follow this article, start with just the short USBC cable that comma includes (there should be no errors and no need for the coupler when using the short cable). Come back here with any questions.

https://bluepilot.dev/2025/08/15/i-...r-i-get-a-canbus-error-and-alerts-on-my-dash/

the only cables I’ve seen marked with the lightning bolt and the 4 were thunderbolt cables. Which are the same form factor but not necessarily the same inside.

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[Ajzride]

the only cables I’ve seen marked with the lightning bolt and the 4 were thunderbolt cables. Which are the same form factor but not necessarily the same inside.

Ahh, yes. Thunderbolt 4 is not USB 4.

 

[campalex24]

Ahh, yes. Thunderbolt 4 is not USB 4.

Yes, sorry, brain is fried, meant thunderbolt 4 not usb, and thank you for the replies!

 

[Ajzride]

Yes, sorry, brain is fried, meant thunderbolt 4 not usb, and thank you for the replies!

How did it go using just the short Comma cable?

 

[campalex24]

Currently trying to find my old one since both the new sets they mailed me did not include one

 

[Ajzride]

Currently trying to find my old one since both the new sets they mailed me did not include one

The short cable came with the device, not the harness. Are you swapping over from another vehicle?

 

[campalex24]

Yes, I was

 

[Ajzride]

Yes, I was

If you are in Houston you can come by my place e and test. If not:

https://www.amazon.com/Tan-QY-USB-T...7&sprefix=usb+3.2+gen+2+1.5+ft,aps,199&sr=8-4

 

[campalex24]

Unfortunately in Maine? Although I have this, will it do?

 

[Ajzride]

Unfortunately in Maine? Although I have this, will it do?

Probably

 

[campalex24]

Tysm. It worked. (Well not this one, both the comma cables, 4 other ones I tried, but 2 of the usb-c 3.2 gen 2 I had with a coupler worked!)

 

[Shmoe]

Unfortunately in Maine? Although I have this, will it do?

Probably not, you are quite well stocked in thunderbolt cables

 

[Ajzride]

Tysm. It worked. (Well not this one, both the comma cables, 4 other ones I tried, but 2 of the usb-c 3.2 gen 2 I had with a coupler worked!)

So can you sumarize where you are?

Fully working with no startup errors?

IS this your current wiring?

Q4 Harness --> Harness Box --> Aftermarket USBC 3.2g2 --> Uncle Tony's Coupler --> Aftermarket USBC 3.2g2 --> Comma3x

 

[campalex24]

So can you sumarize where you are? Sure

Fully working with no startup errors? no

IS this your current wiring? yes

Q4 Harness --> Harness Box --> Aftermarket USBC 3.2g2 --> Uncle Tony's Coupler --> Aftermarket USBC 3.2g2 --> Comma3x

** have tried this with two seperate Q4 harnesses, 2 harness boxes, and then:

- Q4 Harness --> Harness Box --> Aftermarket USBC 3.2g2 [cable a] --> Uncle Tony's Coupler --> Aftermarket USBC 3.2g2 [cable b] --> Comma3x

- Q4 Harness --> Harness Box --> Aftermarket USBC 3.2g2 [cable a] --> included comma usb female -female connector --> Aftermarket USBC 3.2g2 [cable b] --> Comma3x

- Q4 Harness --> Harness Box --> Aftermarket USBC 3.2g2 [cable c] --> Uncle Tony's Coupler --> Aftermarket USBC 3.2g2 [cable d] --> Comma3x

- Q4 Harness --> Harness Box --> Thunderbolt 4 [cable T1] --> Uncle Tony's Coupler --> Thunderbolt 4 [cable T2] --> Comma3x

- Q4 Harness --> Harness Box --> Thunderbolt 4 [cable T1] --> included comma usb female -female connector --> Thunderbolt 4 [cable T2] --> Comma3x --this set up i got like 5 minutes down the road and then the errors all kicked on, it was the only one that tricked me into thinking it worked.


***cables a, b, c, d, e etc are all USB C gen 3.2g2;

The only thing I can think is that compared to the video, the outside of the material containing the wiring that I plug the Q4 harness into is silver, not black, although it does have the same ridges.

Also, when the comma is unplugged, sometimes the AC will only blow unchilled air

 

[campalex24]

I also did go and pick up 2 brand new usb c 3.2 gen 2 cables to make sure it wasn’t them

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