Trailer wiring (yes, again) for 2022 R1250 GS/A

[sadlsor]

QUESTION:
How can I tap into a switched power source near the back (such as the running light at the rear brake, or license plate light) without upsetting Mr. BUS of CAN?
The trailer is currently installed with regular incandescent bulbs - NOT LED - but I'm not worried about current draw, with this bike's alternator capacity.
Seems to be a simple question; the trailer lights will switch off with no power, once I switch off the bike power.

Situation:
I've mounted a trailer hitch (Bushtec) to tow my old Roadstar trailer, and I want to wire it and avoid the CANBUS.
Have the trailer wiring harness as well as the universal trailer isolator from Electrical Connection. I have the correct trailer plug connector to fit the trailer as well.

Background:
An electrician friend helped me (really I just watched) install the same components on my ST1300, direct to battery, and it all worked. Yes, I'll route through a fuseblock in the future. Obviously, no CANBUS involved.
Why avoid CANBUS? Two reasons.
1. Fear of the unknown.
2. I don't have an EZcan or similar yet, might use that later on. (See fuseblock remark, above.)
3. Don't want to throw an error code from the bike's brain.

All the (Searched) threads I've found here are several years old, and very non-specific. Likewise, the YouTube wiring how-to's that don't address my bike, and other shortcomings. So, can you kind and knowledgeable riders help me find switched power without blowing the ECU's little mind?
Let's bring this discussion back into the 2020s, much obliged.
As an aside, please don't tell me how many ways it's a bad idea to pull a trailer with a motorcycle. I've read enough of that.
Thank you for sharing your BMW-specific motorcycle trailer wiring experience!

 

[r0ckrat]

If all you need is switched power, use the tail light (not brake light) wire, and run that to a relay's trigger port. The relay doesn't draw power (at least not enough to bother canbus), it just uses it to "flip the switch".

 

[jandhumphreyme]

I dont know of any spot that won't alarm the canbus with that many incandescent lights wired in. On my 2018RT i bit the bullet and went with a HexCan, it allowed a quick connection into the electrical system with a dedicated fused power supply. The upside of the HexCan was programmable with different brake light flash sequences.

 

[PoorUB]

If all you need is switched power, use the tail light (not brake light) wire, and run that to a relay's trigger port. The relay doesn't draw power (at least not enough to bother canbus), it just uses it to "flip the switch".

I don't think that will work. I may be wrong, but if the lighting is similar the the RT the tail and brake light are the same bulb. In tail light mod the light gets cycled on and off many times a second. The pulsed tail light looks dimmer as it is on roughly half the time. The brake light is full on.

Does the GS have the round disconnect under the passenger seat for top case lights? If it does I will bet there is a switched 12 volt in that connector. Another option is to run the tail light of the accessory socket power, if the bike has one. I would still use the bike's power to run a relay and power the lights off the battery.

If the OP wants tail, brake, and turn he will need a CANBUS happy taillight isolator.

 

[sadlsor]

Honestly, I haven't dug into the trail light yet or any connectors under the seat.
I was hoping someone had wired a trailer to a 1250 GS or GSA, and I could just duplicate their successful install.
I'm pretty sure I can break something, or cause problems, with trial and error.

 

[pglaves]

If BMW wanted you to pull a trailer they would sell trailers with the wiring already included - at BMW's prices per inch of wire, of course.

 

[sadlsor]

If BMW wanted you to pull a trailer they would sell trailers with the wiring already included - at BMW's prices per inch of wire, of course.

I know. And if BMW wanted us to use a GPS, they would sell us those, too. And if BMW wanted us to carry crap on the bike with us, they would sell us luggage and boxes and bags to attach to the bike.
Oh, wait... never mind.

So here's a Reply from Steve at A Bike Thing, and he believes / opines what I've suspected:

"I never recommend you splice anything in to any wire on your BMW bike. The ezcan will do what you need it to do. It’s a plug and play solution so you can power up lights anywhere on the bike.

The relay option is going to be messier too. Ive even seen low draw trigger wores (sic) cause dash errors on BMW’s so I can’t guarantee you won’t get an error."

Reckon I'll go with what we know works, instead of "figuring it out." I have to rely on Other Peoples' Experience, because there's not enough time left in this life for me to make all the mistakes myself.

But Lord knows it seems like I keep tryin'...

 

[rhbike]

A Canbus controller was always the best solution. With the complexity of modern bike wiring harnesses and how fine the wires are, exposure to mousture and vibration, etc, tapping into the wiring harness is begging for trouble when you least expect it.

 

[guenner]

I used a wire tap to get 12V to a relay. I used the wire at the back of the bike that goes to the license plate light.

I did a bit of testing with that connection on my F700GS. Funny, it didn't give me a LAMP error when I removed the bulb(?). I could draw ca. 2A without a problem...good enough to activate a relay. I assume the limit is 7.5 A as with most other wires. But I didn't go that far with my test since I found no documentation about details on the license plate wiring.

Btw, the Canbus is just the connection between the various computers on your bike. The computer that controls most of non-motor related electrics on the bike is the ZFE (Zentrale Fahrgestell Elektrik or central vehicle electric).

 

[sadlsor]

A Canbus controller was always the best solution. With the complexity of modern bike wiring harnesses and how fine the wires are, exposure to mousture and vibration, etc, tapping into the wiring harness is begging for trouble when you least expect it.

Although I usually take the hardest path for the simplest tasks (can't help it; genetic defect I guess), this time I've now ordered the ezCAN from BeemerWorks.
I was really surprised there were / are no YouTube videos with a step-by-step for doofuses on how to wire a trailer to a CANBUS system. Open Road Outfitters comes the closest.
https://openroadoutfitters.com/
And as you can imagine, all the usual suspect forums and online communities were likewise all over the map with opinions and theories, but no "here's how I did it" replies.
I'll follow up here with *my* how-I-did-it.

 

[PoorUB]

I dragged a Unigo trailer with my 2018 R1200RT. I put LED light bulbs in the sockets and wired it directly to my RT. I pulled it many miles this way with zero issues. If you are running incandescent lights you need a controller.

I have since bought a 2023 Goldwing and wired a powered tail light isolator this time. People get all bent out of shape with the CANBUS and BMW's ZFE. You can add a minimal load, and not trip the controller, but minute. Incandescent bulbs draw to much power.

Also, people get scared of frying the computer on the bike. Unless you do something really stupid you won't hurt anything. I had a 2016 Harley with CANBUS. I bought what was supposedly a CANBUS friendly taillight isolator and it made the computer do all kinds of wonky stuff. I get the correct isolator and it worked fine. The incorrect isolator didn't damage anything.

 

[jandhumphreyme]

Although I usually take the hardest path for the simplest tasks (can't help it; genetic defect I guess), this time I've now ordered the ezCAN from BeemerWorks.
I was really surprised there were / are no YouTube videos with a step-by-step for doofuses on how to wire a trailer to a CANBUS system. Open Road Outfitters comes the closest.
https://openroadoutfitters.com/
And as you can imagine, all the usual suspect forums and online communities were likewise all over the map with opinions and theories, but no "here's how I did it" replies.
I'll follow up here with *my* how-I-did-it.

You'll make out ok. I watched the open road outfitters video before I wired mine in. The EzCan is very straight forward with good instruction you won't have any issues.

Couple of things that I did. I bought a roll of Tessa Tape to wrap my wiring harness and used ring terminals bolted them together for my common, wrapped that with 3m Super 33+ to insulate. I found a spot between body panels for wire loom to exit so no drilling holes in the body.

I only ran my minimate for one season, I'm prone to fits of invincibility and I figured it was only a matter of time before I did something really stupid pulling that thing, and I'd wake up in a ditch, if I woke up. I never had any accidents but it made me uncomfortable enough, pushing me into corners that I sold it. As far as camping goes, man I loved that thing, it took all of 5 minutes to set up, and not sleeping on the ground was great. I may buy another one someday when I slow down or finally go on three wheels.

Looking forward to your photos, good luck.