WattTruckMatt's El Cap Granite R1T Journey & Build Journal

[WattTruckMatt]

For what its worth, my DCE brackets also wobble.

I had ditch lights on my Grand Cherokee and they were rock solid and the design was very similar, so maybe the hood/ hinges on the Rivian are not as stout as on other vehicles?

Yeah my old Tacoma ones were rock solid as well. I have found a couple ways to handle the wobble with these. I’ve used a mixture of rubber bumpers and “spacers” to take up the slack in the metal… if that makes sense. The brackets would need an extra bracket to connect to the hood with 3M tape or something, but the welding necessary would make these pricey I’m sure.

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[ORFynder]

I recently got a WeBoost system in preparation for upcoming Colorado and West TX roadtrips. In doing so, I decided to redo my original Midland MXT575 install and run power from the 12V battery through the firewall to a space behind the rear seats. I was able to run the WeBoost antenna cable the same way I did for the GMRS antenna.

Not many have done the firewall passthrough so don't hesitate if you have any questions. I ran power to my Garmin Powerswitch in the frunk that I was using for my ditch lights. Idea was to have a "Comms" toggle that turns on both the MXT575 and WeBoost.

Thanks for the write up @WattTruckMatt . Had a question: For the weboost exterior antenna cable, did u have to cut it to in order to phish it thru to the back seat grommet? Thanks again!

 

[WattTruckMatt]

Thanks for the write up @WattTruckMatt . Had a question: For the weboost exterior antenna cable, did u have to cut it to in order to phish it thru to the back seat grommet? Thanks again!

I did cut the antenna cable to get it through that small hole at the bottom of the window. I was able to reuse the metal coax connector.

 

[mike813]

Great details - thanks to the OP for sharing and thanks all for the info and knowledge. I bought the little Midland MXT275 for my R1S. Since my only 12V is in the rear (thanks RJ!?!) I've got the 12V plugged in in the cargo area. I have the antenna run out the back hatch. The roof trim piece with the dorsal antenna isn't metal, so I placed the antenna on the metal roof piece between the two roof glass panels, then ran the antenna cord back in the channel along the roof glass. I have the wires run under the third row seat and the radio unit under the second row seat with a CAT6 cable extension up to the front. I'm currently in a R1S loaner while mine is in service, so this is all temporary testing for now. When I get mine back I may try to find a bit more permanent solution. I won't permanently mount the antenna, just leave it inside somewhere (maybe one of the third row candy holders by the cupholders, or maybe even behind the trim by the air compressor, or maybe down in the spare tire cavity) and then mount it when in use. I'd like to mount the radio base unit somewhere and hard wire the power, so I'll do some more research about tapping in to fuses. I tapped in to the rear view mirror for my radar detector and I'm happy with the results, hopefully I can find some similar guidance on these forums somewhere for hard wiring this unit. My MXT275 is the lower power version of the OPs unit, so lower power draw.

 

[zonehawk]

I recently got a WeBoost system in preparation for upcoming Colorado and West TX roadtrips. In doing so, I decided to redo my original Midland MXT575 install and run power from the 12V battery through the firewall to a space behind the rear seats. I was able to run the WeBoost antenna cable the same way I did for the GMRS antenna.

Not many have done the firewall passthrough so don't hesitate if you have any questions. I ran power to my Garmin Powerswitch in the frunk that I was using for my ditch lights. Idea was to have a "Comms" toggle that turns on both the MXT575 and WeBoost.

Had a couple questions for you if you didn't mind!
Can you confirm that this passthrough goes into the passenger footwell? Also curious your wiring path from the back seats to this passthrough in the firewall, did it run under the door sills and over?

Also looks like the Garmin is connected to the final positive terminal, any reason for that over the empty middle or other two? I've done similar wiring in past Toyotas but those had traditional 12v batteries, not these two separate ones, so want to make sure I'm not missing something about this set up. Also did you have to tap into any fuses for the garmin system, to not have it drain the 12v?

Thank you for taking the steps and documenting them, it's super nice to reference as I have a WeBoost, Midland radio, and some lights I've been wanting to put in this Rivian for the last year.

 

[WattTruckMatt]

Had a couple questions for you if you didn't mind!
Can you confirm that this passthrough goes into the passenger footwell? Also curious your wiring path from the back seats to this passthrough in the firewall, did it run under the door sills and over?

Also looks like the Garmin is connected to the final positive terminal, any reason for that over the empty middle or other two? I've done similar wiring in past Toyotas but those had traditional 12v batteries, not these two separate ones, so want to make sure I'm not missing something about this set up. Also did you have to tap into any fuses for the garmin system, to not have it drain the 12v?

Thank you for taking the steps and documenting them, it's super nice to reference as I have a WeBoost, Midland radio, and some lights I've been wanting to put in this Rivian for the last year.

- Yes the firewall passthrough is right above where your left foot would be in passenger footwell.
- I ran the wiring under the door sills. Tight fit but I made it work. All the panels pop off like any other vehicle.
- I connected to that particular 150a nut on the 12V battery because that's what someone else on here had done with the same Garmin unit.
- Didn't have to tap into any fuses or anything like that. I haven't had any issues.

 

[tylerdurden03]

I’ll probably win the award for dumbest question on this post with this but what is the does the Hitch Slider do? Protect the hitch when off road?

 

[WattTruckMatt]

I’ll probably win the award for dumbest question on this post with this but what is the does the Hitch Slider do? Protect the hitch when off road?

Yeah that's sort of the idea. Protects the hitch/bumper on steep departure angle situations.

On most body-on-frame trucks/SUVs, the hitch hangs the lowest so you'll hit that before the bumper. Different on the Rivian with the tucked up hitch.

 

[mike813]

For anyone with a R1S stumbling on this thread like I did... the Midland MXT275 box fits great in the third row passenger box by the cupholder. I've got mine in that box with the 12V plugged in to the power plug and the antenna run up through the liftgate. I've got a 10' RJ45 extender cable run up to the drivers seat where I can plug in the mic. A very clean temp install until I make the time to install the garmin or some other bus controller like the OP. Man I wish Rivian would have built in the ability to easily add and power accessories like this... oh well, that's what we have forums for!

 

[sac602]

plugged into the 12v by the compressor or the usb-c?

 

[mike813]

Sorry to jump on Matt's post yet again but this has been the best post I've found for GMRS radio install and I haven't done enough hard wire work yet for my own build post. Sharing my photos of pre-hardwire for the Midland MXT275 GMRS in my R1S. I just ordered the better antenna package and I'll probably make a semi-more permanent antenna install this weekend and at least hide the antenna cable behind the trim. While I'm at it it would be nice to hide the power cord - if anyone readying this has any ideas for tapping in to switched power behind this area please let me know - maybe I could just tap in to the power feed that powers this 12V, and then route the power and my antenna hidden, and leave the radio either in this little box, or even better mount it to the side of my spare tire well where it is hidden but can still breathe a bit (not that this simpler 15W version generates that much heat)...

,

 

[WattTruckMatt]

Quite a lot to update but currently working on adding some Morimoto lights to my Xtrusion Overland bed rack.

Amber spot chase light and some "scene" lights. I've also gone from 4 bangers to 2 bangers for ditch lights. That way I don't get any light bounce on bumps and while offroad. Went from s00nish ditch light brackets to some from M&R that I had to modify.

I have the light wiring harness built for the rack and now I need to drill through the small corner panel by the rear window to get my wires into the cab. I will be using my existing grounding block behind rear seats (using for WeBoost and Midland GMRS radio) and pulling power wires all the way through the firewall and to my Garmin PowerSwitch in the frunk area.

More photos when all is completed.

And a beauty shot just because.

 

[HighVoltOverland]

Quite a lot to update but currently working on adding some Morimoto lights to my Xtrusion Overland bed rack.

Amber spot chase light and some "scene" lights. I've also gone from 4 bangers to 2 bangers for ditch lights. That way I don't get any light bounce on bumps and while offroad. Went from s00nish ditch light brackets to some from M&R that I had to modify.

I have the light wiring harness built for the rack and now I need to drill through the small corner panel by the rear window to get my wires into the cab. I will be using my existing grounding block behind rear seats (using for WeBoost and Midland GMRS radio) and pulling power wires all the way through the firewall and to my Garmin PowerSwitch in the frunk area.

More photos when all is completed.

And a beauty shot just because.

which we boost antenna is that?

 

[WattTruckMatt]

which we boost antenna is that?

I bought it from Powerful Signal.

It's a Top Signal 5G OTR Antenna 600–4000 MHz SMA-Female TS210401
https://powerfulsignal.com/top-signal-5g-otr-antenna-600-4000-mhz/

 

[sevrsnape37]

I bought it from Powerful Signal.

It's a Top Signal 5G OTR Antenna 600–4000 MHz SMA-Female TS210401
https://powerfulsignal.com/top-signal-5g-otr-antenna-600-4000-mhz/

That’s one beefy girl!

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