Comma AI self driver assistant

[B177y]

I got my Comma 4 last night @Ajzride was a huge help and great resource. It's amazing I'm super happy with it as a first time Comma user.

Oh man, I didn't need to see this... Love the small screen compared to my 3x.

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[B177y]

I tried to write a summary on getting things going on the C4, let me know if anyone thinks of something I should add:

https://bluepilot.dev/2025/12/17/bluepilot-on-the-comma4/

Excellent info. Allows me to not want to immediately upgrade to the small screen.

 

[Ajzride]

Oh man, I didn't need to see this... Love the small screen compared to my 3x.

You give up all the UI goodies though.

 

[B177y]

You give up all the UI goodies though.

Yeah, after reading your follow up post it's worth waiting or keeping the 3x until it becomes obsolete.

 

[DIEProphezeiung]

Yeah, I'm going with bad comma3x. I've had it up and running for almost a year with little to no issues until recently. I originally had a modified (extended with resistors) Ford Q4 harness. Bought a new harness and lightning adapter to eliminate that. So I have all new everything except the comma3x itself, which was bought on black friday last year.
Suppose Ill get a support ticket with them started.

It turns out it was the Comma3x that was faulty. Got it sent in a few days before the warranty expired, and they ended up just sending me a new device. I know this because it has a different ID and doesn't show my previous trips. I also have the new harness installed with the lightning adapter, so I can't confirm if the old modified harness is what caused the issue in the first place, but everything is working now. Thanks for all the help with troubleshooting.

That being said, I do have a question about ping-ponging on BP5.0. I reviewed the thread again after the BP5 release and haven't seen it mentioned. Apologies if it's already been asked, but are there settings that can curb the ping-pong I'm experiencing? I have reviewed the settings in the comma, and nothing stood out as likely to help.

I just got the replacement comma installed yesterday, so I haven't changed any of the defaults after the fresh BP5.0 install, other than adjusting in-lane offset slightly.

Edit:
I see the sugestion to try different models now. I will check what model is loaded (firehose i think) and try and change it to WD-40 as suggested.

 

[Ajzride]

It turns out it was the Comma3x that was faulty. Got it sent in a few days before the warranty expired, and they ended up just sending me a new device. I know this because it has a different ID and doesn't show my previous trips. I also have the new harness installed with the lightning adapter, so I can't confirm if the old modified harness is what caused the issue in the first place, but everything is working now. Thanks for all the help with troubleshooting.

That being said, I do have a question about ping-ponging on BP5.0. I reviewed the thread again after the BP5 release and haven't seen it mentioned. Apologies if it's already been asked, but are there settings that can curb the ping-pong I'm experiencing? I have reviewed the settings in the comma, and nothing stood out as likely to help.

I just got the replacement comma installed yesterday, so I haven't changed any of the defaults after the fresh BP5.0 install, other than adjusting in-lane offset slightly.

Edit:
I see the sugestion to try different models now. I will check what model is loaded (firehose i think) and try and change it to WD-40 as suggested.

WD-40, Filet o Fish Liquid Crystal, North Nevada v2 should all be a big improvement over firehose. If you need to adjust tuning, Predicted Curvature Blend Ratio is the one to mess with:

https://www.f150gen14.com/forum/thr...fork-for-comma3x-openpilot.24241/#post-457708

 

[B177y]

It turns out it was the Comma3x that was faulty. Got it sent in a few days before the warranty expired, and they ended up just sending me a new device. I know this because it has a different ID and doesn't show my previous trips. I also have the new harness installed with the lightning adapter, so I can't confirm if the old modified harness is what caused the issue in the first place, but everything is working now. Thanks for all the help with troubleshooting.

That being said, I do have a question about ping-ponging on BP5.0. I reviewed the thread again after the BP5 release and haven't seen it mentioned. Apologies if it's already been asked, but are there settings that can curb the ping-pong I'm experiencing? I have reviewed the settings in the comma, and nothing stood out as likely to help.

I just got the replacement comma installed yesterday, so I haven't changed any of the defaults after the fresh BP5.0 install, other than adjusting in-lane offset slightly.

Edit:
I see the sugestion to try different models now. I will check what model is loaded (firehose i think) and try and change it to WD-40 as suggested.

For me, WD-40 is consistently the best model. I have tried FoF and North Nevada v2 on @Ajzride's recommendation with BP 5.0, but I get side to side drift/ping-pong with both of those models. For whatever reason, WD-40 is rock solid on my Lightning.

 

[EVO]

WD-40 works best for me.

 

[itsjmod]

Reverting my poor harness back to the OBD-C original location while I wait for my new harness from Comma since I have the coupler now

I’m getting better at soldering and this wiring stuff though which is good.

Question - is the coupler supposed to work on just normal power or does it need the expected voltage from the truck? Neither the comma or anything else turns on or charges using it in the middle of any 2 USB-Cs. I’ve tried plenty of verified 3.1 Gen 2s of different sizes and using the stock comma angled short cord on the last mile. No device or the comma gets power

Want to rule out a possible faulty coupler as I’m doing this wiring cause I’ll order a new one if this isn’t expected, but I reckon Ill find out in the next few days when I try to connect it all up anyway haha

 

[itsjmod]

Oh and I’m soldering the wires and just super gluing the screws on

 

[B177y]

Reverting my poor harness back to the OBD-C original location while I wait for my new harness from Comma since I have the coupler now

I’m getting better at soldering and this wiring stuff though which is good.

Question - is the coupler supposed to work on just normal power or does it need the expected voltage from the truck? Neither the comma or anything else turns on or charges using it in the middle of any 2 USB-Cs. I’ve tried plenty of verified 3.1 Gen 2s of different sizes and using the stock comma angled short cord on the last mile. No device or the comma gets power

Want to rule out a possible faulty coupler as I’m doing this wiring cause I’ll order a new one if this isn’t expected, but I reckon Ill find out in the next few days when I try to connect it all up anyway haha

If I am following correctly, you're asking if the Comma will power on if you add the coupler to a USB cord that is plugged in to a USB power source like a phone charger, not the truck?

 

[itsjmod]

If I am following correctly, you're asking if the Comma will power on if you add the coupler to a USB cord that is plugged in to a USB power source like a phone charger, not the truck?

Correct. Like using it in my house. I thought it should work so I was trying to test but no dice. I’ll admit I’m not too versed on resistors. But yes -

MacBook brick → any USB-C → coupler → Comma stock short cord → Comma = no power

brick → any USB-C → coupler → Comma stock short cord → iPhone = no power

brick → any USB-C → Comma = power. Etc etc

I tried other bricks of various power output too

 

[chriserx]

Correct. Like using it in my house. I thought it should work so I was trying to test but no dice. I’ll admit I’m not too versed on resistors. But yes -

MacBook brick → any USB-C → coupler → Comma stock short cord → Comma = no power

brick → any USB-C → coupler → Comma stock short cord → iPhone = no power

brick → any USB-C → Comma = power. Etc etc

I tried other bricks of various power output too

Afaik it needs to be a 'dumb' power supply like what a raspberry pi 4 had to use since iirc it doesn't use the actual USB spec.
Note: I've never actually tried this, and is an educated guess.

Edit: You only need the resistor/coupler for communication with the truck. You won't need it in the house.

Edit 2: The 'dumb' power supply will likely also need to supply 12v on the line and not 5v.

 

[B177y]

Correct. Like using it in my house. I thought it should work so I was trying to test but no dice. I’ll admit I’m not too versed on resistors. But yes -

MacBook brick → any USB-C → coupler → Comma stock short cord → Comma = no power

brick → any USB-C → coupler → Comma stock short cord → iPhone = no power

brick → any USB-C → Comma = power. Etc etc

I tried other bricks of various power output too

Agree with everything @chriserx said except for "Edit 2". You can use a 5 volt USB when powering the Comma outside of a vehicle, you just have to accept the low voltage warning on the Comma. I have found that the Comma works best when connected to my powered USB hub on my desktop, but YMMV. Some USB power sources just won't work or will allow boot up but then the Comma shuts down.

When in the Lightning, you need the coupler with the resistor to prevent "CAN reflections" which cause the startup errors (I have no idea what this is, it's just what I've been told). The coupler has to be in the correct orientation as marked on the coupler itself. It can be installed anywhere along the USB lines.

The OBD power that plugs into the Comma harness is optional and is used to keep the Comma powered after you turn off the ignition. Use the OBD at your own risk with the Lightning's tiny 12 volt battery.

 

[Ajzride]

The coupler was not designed to be used with a 5v power supply. It was tuned for 12v in the car, I would expect weird things to happen on a 5v source.

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