Is the trailer hitch on G1 R1S "grounded"?

[srjordan7251]

OK, weird question…Is the trailer hitch on G1 R1S "grounded"?

Reason I ask is…I have an old horse trailer and even after making the electrical hookup to my previously owned Tacoma, the trailer’s 7-pin electrical components wouldn’t work until the trailer’s hitch was attached to the Tacoma’s hitch. I concluded at the time (with no trailer electrical expertise) that the Tacoma hitch was providing some grounding that wasn’t happening through the electrical hookup.

Now I’m trying to use the R1S with this trailer and the trailer running and brake lights won’t work. Oddly, the trailer brakes are working fine. Which makes me question whether my prior assumption about grounding made any sense.

I use the R1S with a 4-pin trailer all the time and all the lights work fine there. So I don’t think the problem is on the R1S side. And obviously I could just have a new failure somewhere in the trailer wiring. (and I don’t have access to another vehicle with a 7-pin trailer connector.)

Any advice would be appreciated. Thanks.

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[VandalSibs]

OK, weird question…Is the trailer hitch on G1 R1S "grounded"?

Reason I ask is…I have an old horse trailer and even after making the electrical hookup to my previously owned Tacoma, the trailer’s 7-pin electrical components wouldn’t work until the trailer’s hitch was attached to the Tacoma’s hitch. I concluded at the time (with no trailer electrical expertise) that the Tacoma hitch was providing some grounding that wasn’t happening through the electrical hookup.

Now I’m trying to use the R1S with this trailer and the trailer running and brake lights won’t work. Oddly, the trailer brakes are working fine. Which makes me question whether my prior assumption about grounding made any sense.

I use the R1S with a 4-pin trailer all the time and all the lights work fine there. So I don’t think the problem is on the R1S side. And obviously I could just have a new failure somewhere in the trailer wiring. (and I don’t have access to another vehicle with a 7-pin trailer connector.)

Any advice would be appreciated. Thanks.

I would lean towards some new issue with your trailer wiring...

If there's an RV dealership near you with a service department, swing by and ask if they can test your 7-pin connector on the R1S real quick. That would be useful info.

 

[csharp]

Sounds like a trailer wiring problem to me, especially since some things work and others dont. As @VandalSibs mentioned, take it to an RV dealer / shop near you and they can easily test. Also, sometimes AutoZone, Advance, etc will have testers. Worse case scenario, break out the voltmeter and test your R1S, then you can at least eliminate that as the culprit.

 

[dduffey]

I think your already suspected what is likely happening: There is an issue with the 7 pin connector ground (pin 1) either in the trailer wiring or is not grounded to the trailer at all.

You could test this with a voltmeter between pin 1 on the cable and the trailer frame.

 

[srjordan7251]

Thanks for the replies. I did finally find my 7-pin tester and the Rivian checks out fine. I can't count how many times I've had to use a volt meter pin by pin with past trailers, which is a huge chore for me since my electrical expertise is so limited. I was mostly hoping someone had heard of my previous wierd issue with how it suddenly worked once the car hitch was in contact with the trailer hitch. But not many people have likely had that happen. I'll keep playing with things...

 

[VSG]

Could it be a problem with LED trailer lights?
See https://www.rivianforums.com/forum/...er-says-software-fix-could-take-a-year.39808/ and similar threads.

 

[VandalSibs]

Could it be a problem with LED trailer lights?
See https://www.rivianforums.com/forum/...er-says-software-fix-could-take-a-year.39808/ and similar threads.

That one is so weird, as all of the lights on my RV Trailer are LED and I've never had an issue with them. My wife and I check them every time we hitch up and move (even if it was just a drop to charge up the truck, which luckily has happened only once!).

 

[Dark-Fx]

That one is so weird, as all of the lights on my RV Trailer are LED and I've never had an issue with them. My wife and I check them every time we hitch up and move (even if it was just a drop to charge up the truck, which luckily has happened only once!).

I think it has to do with the power-on behavior. It's not uncommon for LEDs to draw very little energy the whole time, which is going to confuse anything that is trying to compare it to an open connection.

 

[josh0]

One thing to consider: was the truck ‘on’? I hooked my trailer up the other day, and thought I wasn’t getting any power through the 7-pin, but it was actually just that I’d closed the truck door and it had turned itself off and shut down accessory power. Opening the door fixed everything.

 

[srjordan7251]

Yes, the Rivian was on. I was driving it, and that's how I know the trailer brakes work.

"I think it has to do with the power-on behavior. It's not uncommon for LEDs to draw very little energy the whole time, which is going to confuse anything that is trying to compare it to an open connection." I know this can be a problem with testers that expect a certain draw that LEDs might not provide. I don't know if this is a problem here, though the Rivian did tell me trailer lights weren't working, which I assume means it did not detect draw from those wires.

I did find a junction box. So at least that makes voltage testing a little easier. The ground wires (white I believe) look okay here. I haven't looked for where the ground terminates yet.

 

[josh0]

Yes, the Rivian was on. I was driving it, and that's how I know the trailer brakes work.

"I think it has to do with the power-on behavior. It's not uncommon for LEDs to draw very little energy the whole time, which is going to confuse anything that is trying to compare it to an open connection." I know this can be a problem with testers that expect a certain draw that LEDs might not provide. I don't know if this is a problem here, though the Rivian did tell me trailer lights weren't working, which I assume means it did not detect draw from those wires.

I did find a junction box. So at least that makes voltage testing a little easier. The ground wires (white I believe) look okay here. I haven't looked for where the ground terminates yet.

You said the 7-pin didn’t work until the hitch was actually attached. So clearly you weren’t driving it when you experienced the problem. Before the hitch was actually attached and you were driving it, are you positive it was on?

 

[Zoidz]

I've expereinced this problem many times over the years with mutiple, older trailers. The trailer hitch is grounded, so it provides a ground path along with the white wire. If the white wire has a poor connection somewhere i.e. at the male/female mating pin, the wire terminal inside the plug, or where the white wire attaches to the frame. this problem occurs. In your picture, I see crimp terminals. Over time, they can oxidize inside the wire crimp and cause issues. The brakes should be using a larger gauge wire compared to the lights.

The only realsolution is to inspect every connection in the ground circuit until you find the problem. Check for poor con

 

[dduffey]

Yes, the Rivian was on. I was driving it, and that's how I know the trailer brakes work.

"I think it has to do with the power-on behavior. It's not uncommon for LEDs to draw very little energy the whole time, which is going to confuse anything that is trying to compare it to an open connection." I know this can be a problem with testers that expect a certain draw that LEDs might not provide. I don't know if this is a problem here, though the Rivian did tell me trailer lights weren't working, which I assume means it did not detect draw from those wires.

I did find a junction box. So at least that makes voltage testing a little easier. The ground wires (white I believe) look okay here. I haven't looked for where the ground terminates yet.

You don't need that, just use the voltmeter from pin 1 at the end of the cable (male plug) and then other lead to the trailer a frame exposed metal to see if there is connectivity, while unhitched and not plugged in.

If there is no connectivity then you know your theory is correct, the trailer is not getting grounded until you hitch up. This could be because of a bad cable, or the pin 1 ground wire not being grounded to the trailer, etc.

 

[racekarl]

You said the 7-pin didn’t work until the hitch was actually attached. So clearly you weren’t driving it when you experienced the problem. Before the hitch was actually attached and you were driving it, are you positive it was on?

No, he said that was the case on his previous vehicle (Tacoma)

 

[josh0]

No, he said that was the case on his previous vehicle (Tacoma)

Ah, my mistake! Sorry!

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