Comma harness issues?

[Ingen]

I just did the fuse tap as detailed in the Google Doc. However, I just have one question: there is no need to ground? Is it grounding within the harness and/or within the AXM?

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[gerrylum]

I just did the fuse tap as detailed in the Google Doc. However, I just have one question: there is no need to ground? Is it grounding within the harness and/or within the AXM?

That's correct. There's already grounding in the harness itself.

 

[bryanmtl]

Hey everyone -- thought I'd revive an older thread. I'm back with more (I think) harness issues. After solving my camera fault issues for months with the fuse tap, I did the latest Rivian software update (2026.15.0) with the Comma disconnected from the vehicle, but with the harness in place. Since that time, I have a permanent front camera/front sensor fault.

I've tried reseating all the connections (while in deep sleep), rebooting, etc, but I'm stuck. Has anyone else run into similar issues? I'm trying to avoid taking the harness out completely, but I'm running out of options.

 

[gerrylum]

Hey everyone -- thought I'd revive an older thread. I'm back with more (I think) harness issues. After solving my camera fault issues for months with the fuse tap, I did the latest Rivian software update (2026.15.0) with the Comma disconnected from the vehicle, but with the harness in place. Since that time, I have a permanent front camera/front sensor fault.

I've tried reseating all the connections (while in deep sleep), rebooting, etc, but I'm stuck. Has anyone else run into similar issues? I'm trying to avoid taking the harness out completely, but I'm running out of options

Might need to try a 12v reset?

 

[an-thu-knee]

I recently installed my comma4 and I am having a subtle issue. When the comma4 is not activated (or even unplugged from the usb-c entirely), my steering wheel feels "sticky", like it gets stuck in certain positions, and not smooth like it was before. It only requires slight effort to move it, but it's very annoying and noticeable.

I have the stock comma rivian harness, I am using stock openpilot. I am using a fuse tap provided by Gerry on F34, and I clamped the red wires on the harness to a wago clamp. Can anyone help me troubleshoot this issue or explain what may be happening and what I can do? Thanks

 

[SwampNut]

If the Comma is unplugged, what makes you believe it's the problem? Have you done the disco reboot?

 

[an-thu-knee]

What's the disco reboot?

Because even when the comma4 is unplugged, the harness is still installed. So I was wondering if there is something about that wiring that could be causing a minor interference. I hope not cause it's a pain to redo the plug into the AXM.

 

[SwampNut]

Maybe Gerry can add to this, but I've never heard of the harness doing anything, and I've been around the Rivian-Comma groups since the beginning. When I have had oddities, removing the harness didn't do anything.

Disco or John Travolta reset is when you hold the left steering wheel button and the hazard button until it reboots the entire car. It will be down for five minutes.

 

[LivingInKaos]

That's a huge John Travolta...

 

[LivingInKaos]

I recently installed my comma4 and I am having a subtle issue. When the comma4 is not activated (or even unplugged from the usb-c entirely), my steering wheel feels "sticky", like it gets stuck in certain positions, and not smooth like it was before. It only requires slight effort to move it, but it's very annoying and noticeable.

I have the stock comma rivian harness, I am using stock openpilot. I am using a fuse tap provided by Gerry on F34, and I clamped the red wires on the harness to a wago clamp. Can anyone help me troubleshoot this issue or explain what may be happening and what I can do? Thanks

That's an odd one if it is happening without the comma even in plugged in. The harness is passthru when not engaged, so there shouldn't be anything coming from it.

 

[an-thu-knee]

Weird indeed. I'll try the hard reboot. I'm just hoping I didn't knock a wire or connection lose when installing the harness that is causing slightly more resistance with the steering. I was very careful though

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