Wiring diagram?

[kneebuster]

I know that this is a serious long shot, but does anyone have a wiring diagram, or knowledge of how Rivian uses color coding on their wires. I'm specifically looking for the 4 wires to the right rear tail light. The wires are black, pink (I'd generously call it red), blue with a white stripe, and green with a white stripe. These 4 don't match anything I can find for another vehicle. I'm trying to determine which is the brake signal so I can run a brake light on the upper crossbar of my bed rack. The RTT will block the light above the rear window.

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[RWerksman]

On the wireless charging pad, black and pink were ground and 12V +. The striped lines were unknown. (pictures are in the thread in my signature)

Not sure if that helps, but it's the best I have.

 

[Zoidz]

If you have a VOM or other low voltage electrical tester, stick a pin or needle into each wire, have someone apply the brake, and monitor the voltage from the pin/needle to ground.

 

[Davethadog]

This is pretty common for modern lights. Black is ground, pink/red is 12v constant, the other two are likely flashing/running signals. It’ll be pretty easy to identify with a multimeter.

 

[SACDFJC]

Have you looked at the trailer wiring? That might provide an additional clue and it's easier to probe the plug as opposed to breaching the wire with a pin or probe.

 

[AltaTruck]

I have been looking to do a similar thing due to HitchHauler loaded motorcycle across the back blocking the brake light/turn signals. I started by wiring it into the trailer wiring port but it will trigger the tow mode and eliminates some features such as side sensors. I picked up a Tekonsha Modulite ZCI Zero Contact Interface #119251 unit which will sense the voltage but not interfere with the signal since it is induced. It draws all power directly from the battery and not splicing into the harness wires. I have asked, several times, how to wire and or a diagram and neither the guide nor service would/could help. My truck is leaving for service tomorrow so it may be a week before I can actually get it wired up but I will post it up when I get it done.

 

[FirstStateR1T]

Have you looked at the trailer wiring? That might provide an additional clue and it's easier to probe the plug as opposed to breaching the wire with a pin or probe.

This would be my recommendation as well!

 

[kneebuster]

Thanks for the replies. Trailer wiring doesn't help, and I've done a bunch of searches with no matches to this combination of colors. I tried putting pins through the insulation yesterday before posting, and using a circuit tester, but one wire had constant power, and another caused a fault on the center display. Will try again today.

 

[Blueassassin]

Thanks for the replies. Trailer wiring doesn't help, and I've done a bunch of searches with no matches to this combination of colors. I tried putting pins through the insulation yesterday before posting, and using a circuit tester, but one wire had constant power, and another caused a fault on the center display. Will try again today.

Just buy a pig tail and use the trailer wiring then you don’t have to cut into the trucks wires right. With the cover on no one even sees it.

 

[AltaTruck]

Just buy a pig tail and use the trailer wiring then you don’t have to cut into the trucks wires right. With the cover on no one even sees it.

That's exactly what I did but it triggers the tow mode and interferes with some of the truck's sensor features. The zero contact module should avoid this problem as it pulls from the battery directly. This needs to get straightened out as many will have need of aux lights in the rear due to load configuration. You can't just splice in a wire here and there.

 

[Dark-Fx]

That's exactly what I did but it triggers the tow mode and interferes with some of the truck's sensor features. The zero contact module should avoid this problem as it pulls from the battery directly. This needs to get straightened out as many will have need of aux lights in the rear due to load configuration. You can't just splice in a wire here and there.

The signal wires don't generate enough current to trigger the ZCI sensors, you have to use the power wires to the lights. I haven't tried to figure out a stop+tail for it but brake lights were easy enough. The parking lights in the side lamps don't generate enough current to falsely trigger the ZCI sensor in my setup, so it seems to work either way.

 

[kneebuster]

I did some more surgery, and am even more puzzled. I pulled the right rear light assembly so that I could get to the connector. Here's what I found.

Black - ground
Red -hot, 13.5v. It reads even when the truck is locked and "off"
Green/White - 2.73v
Blue/White - 2.26v

Those last two have me wondering if they're using digital logic and a microcontroller in the light assembly. I've never heard of that, but I suppose it's possible.

 

[kneebuster]

I then tried tapping into the brake pin on the trailer plug (without touching any other pins) and as AltaTruck said, the truck then asked if I wanted to switch to towing mode.

 

[kneebuster]

Here's why I wanted the aux brake light...

 

[kylealden]

Here's why I wanted the aux brake light...

Do you have a thread about this rack anywhere? Would love to learn more!

FWIW I have the same towing mode problem with my bike rack which has a brake light. I raised in a Reddit AMA with their VP of software engineering and he seemed receptive to adding a towing mode override for this scenario:

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