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CANBUS will know and probably not care; however, your ECM or BCM may care and not like it. CANBUS is just the conduit to/from the ECM/BCM that reads the signals and resistance to various electrical components.
It is always a gamble, it may or may not work if the electrical components you are adding are not compatible with the current system. Tested plug & play from a reliable manufacturer is always the best.
The BCM has circuitry that protects itself from over current events, the most severe being a short circuit. It is also able to detect open circuits when there is no current draw, e.g. when a bulb fails. This isn't CAN bus just electronics.
The CAN bus part is the hand controls, for example, to the BCM where the switches call for a message to be sent to the BCM to be decoded and enacted on.
Last edited by Andy from Sandy; Sep 18, 2025 at 03:57 AM.
Cutting into any wiring harness should never be done (in my opinion), there is always a way to get power without cutting into a harness (not an opinion).
Last edited by Dan89FLSTC; Sep 18, 2025 at 06:48 AM.
Do it the old fashion way. Pleanty of #14 automotive wire, Some 15 amp in line fuses , a switch, some ring terminals to the battery, solder, shrink wrap and tie wraps.
Now you could get fancy and tap off the head light power wire to the low amp side of the input or primary side of a relay you add.
The modern system is not going to see that I wouldn't think. The input side of a relay only draws 1/100 of a amp or so. That won't hurt in pre-CANBUS
Now the input side of a relay does have a lot of resistance. Would that trigger a fault? That answer will have to come from the modern experts.
Be neat ....Keep it legal.
Last edited by Jackie Paper; Sep 18, 2025 at 07:14 AM.
I know that my 2019 FLHTP has accessory plugs available in the fairing. Those can be used for LED lighting. I have also known folks to run power from the battery, use relays and the accessory plug to control lights.
I would hesitate to splice wires into the CAN system as those splices will increase cause issues eventually. They did so even with the older type wiring.
Let's give a simple example:
-The pilot operates the left turn signal switch.
-The handlebar button module sends the message "flashing button activated" to the network.
-The BCM (electric controller) reads this message and energizes the indicators on the indicated side, it also searches for the speedometer signal and also that of the inclination sensor, thus determining how long the indicator will remain on.
-At the same time, the speedometer also reads the message and turns on the dashboard indicator light.
All these messages are sent through a cable, called the “Data Bus”, which is a kind of Internet inside the motorcycle, which allows the modules to communicate with each other.
A fuller explanation of what I posted and I repeat adding extra wire that powers a lamp or additional lamps is not the CAN bus part of the BCM.
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