Rooftop Tents blocking brake lights (CHMSL)

[Dark-Fx]

Wow! ...quite a report. Thanks for your intel and props to your perseverance on this. Why in the name of God would you design an "Adventure Vehicle" and not include 12V connections for accessories in the bed?!? ...at what point do you resign to an external battery for your accessories?

It's not strictly necessary but you can reduce the amount of drain on the primary 12V system, which leads to activating the HV battery and using more energy out of the traction battery. With an auxiliary system using an LFP chemistry, you can pretty much drain the thing completely dead and recharge it without damaging it when it's more convenient. Like when you're actually driving, so the HV system is already activated.

If you buy a high-end bicycle, they don't come with pedals because there are a lot of style of pedals and most of the time the ones they *might* ship with will end up discarded.

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[Dark-Fx]

Sit rep: spent about 7 hours straight yesterday working on this project. Some things I can confirm:

• Even though you can pull a stable 13 volt from the power leads in the tow harness, you can't put any load on it in the absence of signal wire controls. Doing so will cause something on the truck side to freak out, and it goes into some weird pulsing state for a while.
• There are no suitable 12 volt sources in the bed. Anywhere. The closest thing I could find were the leads servicing the gear guard lock next to the bed compressor, but those are just 20 gauge wires and not designed to handle any sort of real amperage required by the Tekonsha (119250).

If you're running wire all the way forward, you could run it next to the air lines on the passenger side of the truck, above the frame rail next to the traction battery. Fish tape to pull it through. I'm planning on trying to run an 8 awg wire through this space to my dc-dc converter for powering the aux battery setup but I haven't done it yet.

• You must remove all the plastics from inside the bed, starting with the forward-most panel labeled "Rivian." This requires a variety of tools, including a Torx T50, T29 (or T28, can't remember), socket set, and panel puller tool. You'll also need to pull panels from inside the gear tunnel (driver's side), rear seat, B-pillar, and A-pillar in order to run a new 12V line allllllll the way from the frunk. Plan on 30 feet of 12 guage wire to get out there, including connectors, heat shrink, etc.

It might be easier to do this from the underside of the truck by removing the underbody panels. You might be able to fish the wire up through the top of the rear quarter with fish tape. Worst case it's enough to just loosen the driver's side bed panel without needing to completely remove it.

I have the side and back wall of the cab plastics off pretty regularly though, planning on not using them when I finish up my sliding bed storage since there's more "space" without them and I'll need to relocate the compressor and 120V stuff to retain access to it anyway. I'm tempted to try to take the bottom panel out and set up my truck so the spare can be dropped out the bottom instead of having to put it under the bed cover, which will require emptying the bed out to get access to it, but that might be a "next year" thing.

• You should avoid tapping off the 12V plug in the gear tunnel, because the Tekonsha requires constant 12V power, otherwise it will go through a re-initialize cycle every time you turn on the vehicle. The 12v in the gear tunnel is switched.
• Do not. Mount. Anything. Until you have a functioning solution. It is guaranteed to not work. Ask me how I know.

My install still does not work, and I expect to be tearing the whole thing apart again this week, some time. TLDR; if you want to install a functioning third brake light, plan way ahead, own a garage, buy many tools, dedicate an entire day, and expect to fail.

The re-initialize doesn't seem to matter with how I have my setup done. Maybe the first blink will get missed but you have to have activated the turn signal lights to get the truck out of park anyway. Definitely good advice to test before putting everything back together though.

 

[Foobar]

Anyone consider using a wireless/rechargeable/accelerometer based solution similar to what they have for motorcycle helmets these days?

 

[avigneault]

The re-initialize doesn't seem to matter with how I have my setup done. Maybe the first blink will get missed but you have to have activated the turn signal lights to get the truck out of park anyway.

I do wonder what's actually going on here, if it's flashing to memory or something. If that's the case, I would be concerned that the device itself would eventually stop working, as some types of flash memory have limited write cycles; I.E, the device can only be re-initialized a certain number of times (perhaps hundreds), after which it self-destructs.

 

[Dark-Fx]

I do wonder what's actually going on here, if it's flashing to memory or something. If that's the case, I would be concerned that the device itself would eventually stop working, as some types of flash memory have limited write cycles; I.E, the device can only be re-initialized a certain number of times (perhaps hundreds), after which it self-destructs.

If it's losing the information after it loses power, I doubt it'll be subject to this, but I've definitely seen stranger things happen. So far mine has been fine after being used for a few months short of a year.

 

[FirstStateR1T]

Anyone consider using a wireless/rechargeable/accelerometer based solution similar to what they have for motorcycle helmets these days?

I too am considering the same solution since my rack use is limited and I can easily charge it up prior.

 

[avigneault]

I looped it over the grey wires at the rear lamps

Okay, I presume you're talking about the black lead here on the right?

 

[Dark-Fx]

Okay, I presume you're talking about the black lead here on the right?

That looks grey to me. I pointed it away from the connector. Might be able to loop the pink/blue and point it at the connector but I never tried that.

 

[Thedude]

I wouldn’t worry about this at all. Thousands, maybe hundreds of thousands of trucks have RTTs over the bed and aren’t being constantly rear ended.

 

[Dark-Fx]

I wouldn’t worry about this at all. Thousands, maybe hundreds of thousands of trucks have RTTs over the bed and aren’t being constantly rear ended.

Rivian's stop lamps are pretty dull if the center stop isn't being illuminated. I'd rather err on the side of blinding the people behind me who have their faces stuffed in their cell phones.

 

[avigneault]

That looks grey to me. I pointed it away from the connector. Might be able to loop the pink/blue and point it at the connector but I never tried that.

I'm partially color blind, so just wanted to make sure "gray" meant dark gray, not light gray. Presumably the pink/light gray wire is the brake light?

 

[Dark-Fx]

I'm partially color blind, so just wanted to make sure "gray" meant dark gray, not light gray. Presumably the pink/light gray wire is the brake light?

The thick wires (gray or what you called black) and the opposite wire which has a pink stripe, are power and thin (two middle wires) ones are communications I believe. Not 100% certain since I didn't scope them out.

 

[avigneault]

The thick wires (gray or what you called black) and the opposite wire which has a pink stripe, are power and thin (two middle wires) ones are communications I believe. Not 100% certain since I didn't scope them out.

I think the two green wires are ultra low voltage to run the diffused light bar leds.

 

[strykerwsu]

This is the way. I know, someone will be concerned about efficiency. I need the fullsize for family. Taking a long trip later in month and will let you all know.

 

[camaroz1985]

This is the way. I know, someone will be concerned about efficiency. I need the fullsize for family. Taking a long trip later in month and will let you all know.

What height is your rack? I keep going back and forth on keeping the tent low, going mid height, or going full height to the rooftop bar height.

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