Comma harness issues?

[bryanmtl]

Make sure you connect those red wires with a Wago or similar connector.

Yup, thanks! Getting one of those today.

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[bryanmtl]

Janka's version is not a magmount and uses a physical USB-C connection. Not the same at all.

Even so, magmounts aren't the culprit in my opinion. Comma issues on Rivian are usually caused by one of three things:

1. Power issue (AXM power connection)
2. Cable issue (bad OBD-C cable).
3. Wake conflict issues (solvable by using F33 fuse for power).

The more I think of it, the more I think I'm suffering from the wake conflict issue. Is there a generally accepted option for a fuse tap with the standard comma harness?

 

[gerrylum]

The more I think of it, the more I think I'm suffering from the wake conflict issue. Is there a generally accepted option for a fuse tap with the standard comma harness?

Best practice is to remove the AXM power connection from the harness, and then use a fuse tap in the F33 fuse location under the passenger footwell. The procedure is detailed in the Installation Tips document.

https://docs.google.com/document/d/1clodGRssTx-dSPSUrQITq_vqumgWcpSUw83zdcAZR-A/edit?usp=sharing

 

[bryanmtl]

Best practice is to remove the AXM power connection from the harness, and then use a fuse tap in the F33 fuse location under the passenger footwell. The procedure is detailed in the Installation Tips document.

https://docs.google.com/document/d/1clodGRssTx-dSPSUrQITq_vqumgWcpSUw83zdcAZR-A/edit?usp=sharing

yeah, great. I removed the AXM power from the harness. Trying to source a fusetap now.

 

[LivingInKaos]

Just be aware the F33 is constant power, so you'll likely want to adjust your max off-road time down to something less than the 30hr default.

 

[godfodder0901]

yeah, great. I removed the AXM power from the harness. Trying to source a fusetap now.

I used this one https://www.amazon.com/dp/B0742BZXC2, recommended by @gerrylum. I then modified the Comma Power harness to get the correct Molex connector.

 

[Singletracker]

Do the cables attached to the Comma Power Molex easily unplug? Also, there are 4 cables attached to the Comma Power Molex. Are they no longer needed when using a fuse tap? Is the fuse tap then the only attachment to the Molex and the harness box, leaving 3 of the 4 Molex ports empty? If so, what are the other Comma Power cables for?

 

[gerrylum]

Do the cables attached to the Comma Power Molex easily unplug? Also, there are 4 cables attached to the Comma Power Molex. Are they no longer needed when using a fuse tap? Is the fuse tap then the only attachment to the Molex and the harness box, leaving 3 of the 4 Molex ports empty? If so, what are the other Comma Power cables for?

OBD signals which we don't use on the Rivian. You just need the red wire for power.

 

[Singletracker]

OBD signals which we don't use on the Rivian. You just need the red wire for power.

Got it! Thanks. We’re I to choose to leave the Comma Power intact, are these the correct Molex connectors?

 

[gerrylum]

Got it! Thanks. We’re I to choose to leave the Comma Power intact, are these the correct Molex connectors?

I use Micro-Fit which I think are a bit smaller than the mini-fit.

https://amzn.to/46hnhW9

 

[Singletracker]

Gerry. are these the correct fuse taps? Amazon indicates that these Micro 2 fuse taps are suitable for my R1T, but I just wanted to verify. Per your suggestion, I will likely also order the Molex Micro connectors. Thanks.

 

[godfodder0901]

Gerry. are these the correct fuse taps? Amazon indicates that these Micro 2 fuse taps are suitable for my R1T, but I just wanted to verify. Per your suggestion, I will likely also order the Molex Micro connectors. Thanks.

No, use the Mini ATM APM ones referenced in my post here https://www.rivianforums.com/forum/threads/comma-harness-issues.54209/post-952589

 

[Singletracker]

Best practice is to remove the AXM power connection from the harness, and then use a fuse tap in the F33 fuse location under the passenger footwell. The procedure is detailed in the Installation Tips document.

https://docs.google.com/document/d/1clodGRssTx-dSPSUrQITq_vqumgWcpSUw83zdcAZR-A/edit?usp=sharing

This document is very helpful, but, IMHO, it leaves out some critical details and should include a procedure for Dummies on exactly how to put together and install a fuse tap connection for the Comma harness. This would include the following info:
1) the exact size/style Molex connector required and how it can be sourced.
2) the exact fuse tap (micro, mini, etc) to use. Will it install into the Molex connector without any modification?
3) the exact amp fuses to use, as it seems like it may depend on where the fuse tap will be installed - F33 or F34.

I realize this is all really simple, not rocket science, and once a person has done, it will be a no brainer. But, if a person has never done it on the Rivian or even had these components in hand, there can be questions, especially when needing to acquire the right items for the job. Just sayin’. For me, I’m a couple of weeks away from receiving my Comma 4 and would like to have everything I need ready to go when it gets here. Anyway, thanks for listening

 

[gerrylum]

This document is very helpful, but, IMHO, it leaves out some critical details and should include a procedure for Dummies on exactly how to put together and install a fuse tap connection for the Comma harness. This would include the following info:
1) the exact size/style Molex connector required and how it can be sourced.
2) the exact fuse tap (micro, mini, etc) to use. Will it install into the Molex connector without any modification?
3) the exact amp fuses to use, as it seems like it may depend on where the fuse tap will be installed - F33 or F34.

I realize this is all really simple, not rocket science, and once a person has done, it will be a no brainer. But, if a person has never done it on the Rivian or even had these components in hand, there can be questions, especially when needing to acquire the right items for the job. Just sayin’. For me, I’m a couple of weeks away from receiving my Comma 4 and would like to have everything I need ready to go when it gets here. Anyway, thanks for listening

I'll write a section on how to build your own fusetap.

 

[Singletracker]

No, use the Mini ATM APM ones referenced in my post here https://www.rivianforums.com/forum/threads/comma-harness-issues.54209/post-952589

According to the Amazon retailer, the fuse referenced in your link, the Mini ATM APM, does not fit the 23 Rivian R1T. They claim it requires their Micro 2 tap. ATP, ATM, APM, ATR, BS, WTF. Heck, I dunno.

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