Need help tricking CANBUS for LED headlights

[Bart Miller]

Hoping to get some input from our electrical and lighting-savvy riders. I have converted and re-wired the stock H7 halogen headlight setup (only one lamp on at a time—either the high beam side or the low beam side) to an H4 LED configuration where both lamps are on as low beam or high beam. Each LED draws 23-24w, so together they must draw about 46-48w. That’s 9-7w less than the single halogen 55 watts the CANBUS expects to find on the circuit, so I’m getting a LAMP! error on the LCD display. Otherwise, I am very pleased with the result. My question: what is the best way to trick the system? Should I add resistors? If so, how many ohms for this particular application? Not sure if off-the-shelf automotive resistors are suitable here. Or would it be better to install CANBUS decoders? For those, I don’t see watt or ohm specs. Are they adaptable to various circuit loads? Thanks!

 

[steve l]

Your description is unclear I assume you are powering a single 24w LED in both reflectors for main beam and in a single 24w LED in both reflectors low beam? H4 LED lamps were never designed to run both low and high circuits at the same time. The lamps would overheat with a possible fire risk.

Fitting H4 bulbs (twin filament) to a reflector designed for H7 bulbs (single filament) may ruin the beam pattern, possibly blinding oncoming traffic.

“re-wired the stock H7 halogen headlight setup (only one lamp on at a time—either the high beam side or the low beam side”
My 2017 model has both H7 lamps on for high beam. The bulb monitoring system will expect to see a 55w load on both low and high circuits for high beam. This may be the source of your LAMP! error rather than the missing 7w load of the new LED lamps. Adding a 20ohm 10watt resistor in parallel with each lamp circuit will bring the load up to the required 55 watt, but the resister will get hot and require a suitable heat sink. Canbus Decoders are simply expensive plug in resistors, they decode nothing.

Hope this helps.

 

[Loudy331]

Hoping to get some input from our electrical and lighting-savvy riders. I have converted and re-wired the stock H7 halogen headlight setup (only one lamp on at a time—either the high beam side or the low beam side) to an H4 LED configuration where both lamps are on as low beam or high beam. Each LED draws 23-24w, so together they must draw about 46-48w. That’s 9-7w less than the single halogen 55 watts the CANBUS expects to find on the circuit, so I’m getting a LAMP! error on the LCD display. Otherwise, I am very pleased with the result. My question: what is the best way to trick the system? Should I add resistors? If so, how many ohms for this particular application? Not sure if off-the-shelf automotive resistors are suitable here. Or would it be better to install CANBUS decoders? For those, I don’t see watt or ohm specs. Are they adaptable to various circuit loads? Thanks!

Did the same last month, fitted the H7 leds but after 5 mins riding I got the lamp error warning.
Bought 2 canbus decoders and no problems since! Hope this helps

 

[Bart Miller]

Thanks, Steve I. I appreciate the info. Only one filament on each H4 bulb is on at any time. But like you said, the reflector buckets were never designed to provide both high and low beam patterns, so that has required adjustment of bulb depth, bucket angle and intensity to avoid blinding oncoming traffic. A LOT of work just to get both lamps on at the same time! Will try your 20 ohm/10 watt resistor/heat sink suggestion! Thanks!

 

[Bart Miller]

Thanks, Loudy331! Glad to hear your decoder install worked for you. I was able to find a set of good-quality decoders at a reasonable price, so I think I'll try them as well as the straight resistor method and see which works best for me. Thanks again!

 

[Delray]

I'm good with basic maintenance, but man, there is some serious geeking-out going on here. Fun to watch.

 

[EvilTwin]

Having once worked at a factory that designed, tested and built automotive headlight assemblies, I saw how critical the designs of the reflector were so that the light output of the bulb would illuminate the road for the driver but at the same time would not blind oncoming traffic. The end result of all that design and testing was a DOT certification for the headlamp assemblies that all manufacturers had to have in order to sell their vehicles. The design was critical to the bulb used. If the filament was out of place by a MM then the light output was not within specs.

Fast forward to today and people are cramming in whatever light bulbs they can buy into existing headlamps and if it lights up the night like its day then all is good.

As an aside, most of the aftermarket lights and lighting assemblies do not get tested or have any sort of DOT approval.

Would love to hear how the OP is re-engineering the reflectors and what testing equipment besides a garage door with tape is being used to accomplish this.

 

[Gerardo]

I am about to intervene the running and brake lights circuit to install a red led strip that I added to the original topcase.
I´ve been always reluctant to do so thinking that canbus will do bad with that.
Any suggestion for doing/not doing that? Thanks!

 

[Bart Miller]

I remember you mentioning your background in lighting on a different thread, Evil Twin. I was hoping you would weigh in. You make a very good point about the work that goes into designing reflectors. I thought about that a lot before I started this project. It's definitely fringe, and my techniques are admittedly rudimentary, but I think I am coming up with a modification that provides good coverage without annoying oncoming drivers. Once I get the last steps completed, I will report back on the results and the whole experience.

 

[Bart Miller]

Gerardo, depending on how big your new LED strip is, it may not affect the original circuit. But you might want to consider an isolation block for your project. I have used them for brake, running and turn signal circuits when adding lights to other bikes. More work but great results. Once wired in, the circuit activates a relay in the block that does not upset CANBUS. Power for the extra light then comes directly from the battery. Will require fishing wires from the back to the battery, but I have found these blocks to work very well. Here is a link. (There are a couple of others I know of, but they are overly-expensive and bike-specific.) You could mount it near the battery/fuse area. ¡Buena suerte!

Show Chrome Electronic Fuse Block - 13-311 Cruiser Motorcycle - Dennis Kirk

Find the Show Chrome Electronic Fuse Block - 13-311 at Dennis Kirk. Shop our complete selection of Cruiser Motorcycle parts and accessories including the Show Chrome Electronic Fuse Block - 13-311.

www.denniskirk.com

 

[Delray]

Quick note for those as clueless as me, this thread sent me to the Google machine. CANBUS = Controller Area Network Bus, with "bus" defined as "a set of conductors carrying data and control signals in a computer system." Basically, the bike's central nervous system.

 

[EvilTwin]

I remember you mentioning your background in lighting on a different thread, Evil Twin. I was hoping you would weigh in. You make a very good point about the work that goes into designing reflectors. I thought about that a lot before I started this project. It's definitely fringe, and my techniques are admittedly rudimentary, but I think I am coming up with a modification that provides good coverage without annoying oncoming drivers. Once I get the last steps completed, I will report back on the results and the whole experience.

I'm curious as to why you want to do this. If it is a case of needing more light at night driving on dark country roads, I would think some aux lighting would be a much better idea. The lights would probably add to the value of the bike if you got some of the higher end name brand versions. Modding the existing headlights may make it hard to sell if a new buyer isn't so keen on the mods. When oncoming traffic shows up, you douse the lights. With modded headlights, you really dont have that option.

Its been a long while (over 20 years ago) but even at the time, the test lab that was used was pretty sophisticated. We had an engineering group that also did the testing for other plants producing "forward lighting". The reflector design was modeled and tested in CAD, then the drawings exported to the CNC mill to make the reflector housing mold. Don't remember if that was done in house or sent out to a vendor. But it was an expensive and time consuming process to get to the point where the housings were spit out of the mold, aluminized and then mated up with the front lens. Creating the lens was another engineering step as well.

 

[freewheelinfrank]

I had my local BMW dealer install a pair of "Cyclops" led H7 lights in my scooter and have not had any problems with the CANBUS.
I also added Denali led aux lights to supplement them.

 

[Pappy13]

I had my local BMW dealer install a pair of "Cyclops" led H7 lights in my scooter and have not had any problems with the CANBUS.
I also added Denali led aux lights to supplement them.

Not wanting to hijack a thread, How do you like the cyclops? My scoot has blown another incandescent low beam headlight and I was looking at the Cyclops as the replacement. All the forums seem to like them, the LED is positioned to reflect as the incandescent and they seem much brighter. I get to go to work very early, I ride in to work in the dark every morning (and before daylight) and I'm down to my last H7. With careful aiming and quality lamps my headlights are adequate, but have a LOT of room for improvement. The Cyclops are "pricey", are they worth it? I had a Daymaker LED in my VTX1800, it spoiled me.

 

[freewheelinfrank]

Not wanting to hijack a thread, How do you like the cyclops? My scoot has blown another incandescent low beam headlight and I was looking at the Cyclops as the replacement. All the forums seem to like them, the LED is positioned to reflect as the incandescent and they seem much brighter. I get to go to work very early, I ride in to work in the dark every morning (and before daylight) and I'm down to my last H7. With careful aiming and quality lamps my headlights are adequate, but have a LOT of room for improvement. The Cyclops are "pricey", are they worth it? I had a Daymaker LED in my VTX1800, it spoiled me.

Yes I like them very much and have had no problems, they install just like the incandescent and should last the lifetime of the bike.

 

[mjnorris]

I ordered a pair of Cyclops and installed them myself. I Han no problems with the canbus.

 

[Minister of Etc]

I had my local BMW dealer install a pair of "Cyclops" led H7 lights in my scooter and have not had any problems with the CANBUS.
I also added Denali led aux lights to supplement them.

Nice. I just received my order from Cyclops last week, and hope to tear down the bike and install them this weekend.

Had a good long pre-sales chat with them before ordering. It sounds like it's going to be a tight fit.

How did you handle installing yours, Frank?

And so this isn't a total hijack, @Bart Miller , I've heard that resistors are sufficient for our C-series CANBUS issues, and that decoders are overkill if you're already getting steady illumination from the bulbs, and just want the dash message to go away.

CANBUS decoders are usually reserved for trickier issues, where you otherwise might need to sacrifice a goat under the light of a full moon.

 

[freewheelinfrank]

Nice. I just received my order from Cyclops last week, and hope to tear down the bike and install them this weekend.

Had a good long pre-sales chat with them before ordering. It sounds like it's going to be a tight fit.

How did you handle installing yours, Frank?

And so this isn't a total hijack, @Bart Miller , I've heard that resistors are sufficient for our C-series CANBUS issues, and that decoders are overkill if you're already getting steady illumination from the bulbs, and just want the dash message to go away.

CANBUS decoders are usually reserved for trickier issues, where you otherwise might need to sacrifice a goat under the light of a full moon.

As I said in my OP I had them installed by my local BMW dealer, but that being said you don't really need to tear down the bike to do it.
Just as with replacing the normal bulbs, you need to take the upper fairing side covers off both sides, this is just to give you a good line of sight to the back of the headlight buckets.
Then reach up from below the headlights to remove the bulbs. Plug in the assembly to the existing wiring after placing the boot on the wiring and sliding it up to the base of the LED bulb.
then just put the bulb into the hole and twist to lock it in place. If you have room you might want to zip tie the extra wiring together to make it look better.

 

[Gerardo]

Gerardo, depending on how big your new LED strip is, it may not affect the original circuit. But you might want to consider an isolation block for your project. I have used them for brake, running and turn signal circuits when adding lights to other bikes. More work but great results. Once wired in, the circuit activates a relay in the block that does not upset CANBUS. Power for the extra light then comes directly from the battery. Will require fishing wires from the back to the battery, but I have found these blocks to work very well. Here is a link. (There are a couple of others I know of, but they are overly-expensive and bike-specific.) You could mount it near the battery/fuse area. ¡Buena suerte!

Show Chrome Electronic Fuse Block - 13-311 Cruiser Motorcycle - Dennis Kirk

Find the Show Chrome Electronic Fuse Block - 13-311 at Dennis Kirk. Shop our complete selection of Cruiser Motorcycle parts and accessories including the Show Chrome Electronic Fuse Block - 13-311.

www.denniskirk.com

Bart, thanks for your advise. I opened the right rear panel and saw the wires, super thin and isolated with a fabric tape. I doubted to open it so I will take a look at your suggestion! Gracias!!

 

[JBChucktown]

I had my local BMW dealer install a pair of "Cyclops" led H7 lights in my scooter and have not had any problems with the CANBUS.
I also added Denali led aux lights to supplement them.

Would love to see you light set up. Thanks in advance.