• Don't overlook our Welcome Package, it contains many links to important and helpful information about functions at VHT like posting pictures and sending PMs (private messages), as well as finding the parts you need.

    AD

Updating to LED turn, brake and indicator lights on CM400T

kbongos

Veteran Member
Joined
May 30, 2022
Total Posts
459
Total likes
163
Location
Minneapolis, MN, USA
I got LED lights in from ebay. Cheapest I could find, in vast quantities to make up for cheapness. For the most part they are working just fine, with a few issues. First was the blinker control issue. The original blinker control only works with original high current bulbs. I knew this, but just forgot about it when ordering LED replacement lights. Started with swapping indicators, that was fine, but getting to blinker and then I recalled how these old blinker controls(in a can) are bi-metal heat up control type and barely work with the original bulbs, assuming all are working and sucking the needed current. So I grudgingly ordered the cheapest electronic one I could find. Plugged it in one way and it didn't work so good, switched connectors around and it was blinking. It even has what looks like a speed control adjuster on it.


$6 - 2-Pin 12V Electronic LED Flasher Relay Fix Turn Signal Bulbs Hyper Flash Issue https://www.ebay.com/itm/124280731352
$7 - 10Pcs 1156 BAY15D 22 SMD LED White Car Bulb Lights Brake/ Stop/ Reverse Lamps US https://www.ebay.com/itm/233654659842
$7 - 20PCS Super White BA9S LED Interior Dome Instrument Panel Dash Gauge Light Bulbs https://www.ebay.com/itm/113967594128
$8 - 10Pcs 1157 BAY15D 22-LED 1206 SMD Brake Turn Signal Light Bulb Lamp White https://www.ebay.com/itm/233474465124

20220729_224336.jpg 20220730_150447.jpg


Now on to the turn signals. When I tried one in front it would blink but would not stay on steady as riding light. These are the 2 element 1157 style. Some troubleshooting showed that these use +12v when turned on, but the turn light element is grounded when no turn switch active(just running light). With independent filaments this is not an issue, but these LED lights just shared the same set of LED's with 2 resistors setting current. And it didn't work with this odd grounding of one. I took the LED light apart and put in a few diodes to fix the issue(thinking I was pretty smart). But then afterwards I figured out I'm not so smart and it would suck to have to do this modification again, and probably a better fix would be to put a diode in the turn signal wire to the front lights so this 'standard' cheap LED light would work. So then I took the time to measure things to determine that turn filament side is problem child that is grounded, running side is fine where it just opens(No Connect) when off. So I would just need diode in turn wire, and that should work even with older bulb in case I want to switch back - might be slightly less bright, no big deal. Plan on doing this, the diodes put in the bulb did work, but I don't want to be taking them apart.


Looking into socket, you have two posts, one deep and at 10:00 position, other shallow(half way at 4:00 position) . This gives run connector on right(9 oclock), turn at left(3:00 oclock). Brake light is similar where left is running light, right is brake. And Brake side and turn are brighter(more current). For 1157 filament I tested and found .56A left, 1.7A right(2.23A both on). For LED replacement measured 54mA and 71mA(108mA together). The back turn lights are only single filament(1156), I measured 1.7A filament, LED replacement was 70mA. Indicator light was 220mA filament, 20mA LED.


I did want to run with old and new in place just to see how they compared. I did a little of this, and thought the LED is vastly uglier and not as gratifying as the slow turn on/off and pleasant spectral quality of the filament. But enough fooling around, I'm going all LED and we will give it time, see how they behave. I'll keep the old just in case the LED's leave me feeling empty inside or break down every 5 miles.


I will have all these extra amps. Hopefully my regulator or stator does not burn out shunting all those un-needed amps back to the stator. Or perhaps I can burn them up in some other useful way, more modernizing gadgets! I like the idea of adding sensors with a smart display, show temperatures, pressures, accurate RPM, the list could go on and on. Welcome to the future my dear vintage honda from the past.

PS. My update where I switched bright and regular wire connect to the headlamp and added toggle switch for bright worked out well. This gives me control of turning headlamp on with bright switch, and indicator light is a bonus telling me my light is on and letting me know if it's not on due to this switch or the flaky starter button it is wired into that I have to giggle. I really don't need a bright(can just manually position headlamp a little while riding), so switch is just as a backup headlamp in case bulb fails.
 
Last edited by a moderator:
Hey @dougrun, Mine is an 81 same as yours but not an automatic. Looks very much like yours at least on the left side. Mine does not have a kick start, I see yours does. I'm very jealous, not sure why, my starter works fine, I just miss having one(had one on a CB500 many moons ago). I watched one of your ride videos, mainly listening to the shifting, and wonder how the 2 speed automatics work. My manual(T) has 5 gears, I am pondering trying a different sprocket size as it's really wound out at 65 MPH highway speed, doing like 6K RPMs. Not that I ride it on the the highway all that much, but it's not like I'm trying to pop wheelies on the thing at low speeds either ;)

How do you like your $20 LED headlamp? That's not a bad price point, I'd consider that over my halogen. But not in any hurry as I don't do much night driving and halogen seems to work fine. Not like I need to save more watts or anything. I'm surprised they can make a LED headlamp that cranks out as much light, they claim twice as much, really?

Your ride did sound nice and quite, I worry mine is getting louder and ponder if I should consider reworking or replacing my exhaust at some point. How many miles you got on it? Mine is at 24K.
 
im at 9k now. probably add 60 tomorrow. I went led for the headlamp mainly for less heat, my headlight wire area is a jungle. Im only in 1st gear at stop signs, the rest is 2nd. i can do 65 easy but would really have to turn the throttle hard to hit 75, but ive done it. The videos are at 4x speed so the sound it hard to follow.
 
Monitor your charge voltage. I went LED (except headlight) on 78 CB400Tii and boiled my battery (good thing it wasn't SLA but regular lead acid). I need to get my Sparks moto rec/reg combo installed or switch back to all incandescent.
 
i went all LED and Lion battery so a compatible rectifier is essential.
 
im at 9k now. probably add 60 tomorrow. I went led for the headlamp mainly for less heat, my headlight wire area is a jungle. Im only in 1st gear at stop signs, the rest is 2nd. i can do 65 easy but would really have to turn the throttle hard to hit 75, but ive done it. The videos are at 4x speed so the sound it hard to follow.
I recently tried to tuck all my connectors back into that headlamp assembly. I thought I had them all in, but then noticed, no there is still one big one missing. I gave up and let all but one connector live outside the headlamp box. I must have pulled them out many years ago so they have been like that for a long while. I did inspect them recently and they seemed to be in reasonable shape - not all oxidized or green. And I have stored my bike in the backyard with a tarp over winter for over 10 years.
 
Monitor your charge voltage. I went LED (except headlight) on 78 CB400Tii and boiled my battery (good thing it wasn't SLA but regular lead acid). I need to get my Sparks moto rec/reg combo installed or switch back to all incandescent.


Thanks for the tip, I will check that over and see what the battery charging level is. I just have basic lead acid battery.
 
Hijacking my own thread here, kind of.
This is a buddy's 81 XL250S. All my LED lights seemed to work despite this being a 6V system.
This bike has 3 independent power systems - one coil for headlamp, one for battery and lights, and another for spark system.
Thought I'd share pics of the bike.

20220731_205231.jpg20220731_205240.jpg20220731_205240.jpg20220731_205248.jpg20220731_205309.jpg20220731_205625.jpg20220731_205339.jpg20220731_205355.jpg
 
So my LED lights in my Y81 CM400T seem to work OK. Now my buddy's Y81 XL250S I have to correct myself, they are not working so great. This is a 6V bike. And the LED's are too dim. I also had a problem with brake light shorting out, which is the two filament 1157 style. This took a while to figure out, all of a sudden none of the light's worked, and I look at the 6v supply and it's just bumping above ground. Did the rotor/stator fail? Did the regulator? Finally disconnected the back brake wires and then I figured out we had a short. Wiggle the 1157 in back and it corrects. Then I dropped his tank on the concrete and added another dent, ugh. Good think it already had 2 big dents in it ;)

So the FSM manual shows that a year later they updated the bike to 12V system.

You can find 6V LED lights, but they are less common so cost 2x-4x the cost of 12V. That would be the recommended solution. I did something weird where I had some odd voltage double 7660 chips and added them to the bulbs. We will see how well those work ;) Not recommended. What might be a better odd solution would be to consider converting to a 12v system with maybe a switching supply.

I did try my hand at modifying the LED to be 6v. The 12V ones I have are arranged with 3 LED's in series, along with a low 60 ohm or so resistor, and I tried cutting and jumper to only 2 LED's in series. But that didn't pan out well, to many LED's and cuts and jumpers.

The 1157 one that replaces 2 separate filaments was a cheapo arrangement with just 2 different resistors to light the same LEDs with
different power levels. For my Frankenstein kludge fix I gave it two separate LED lights.

The small indicator lights worked OK, maybe a little dim, didn't take those apart, I'd guess they probably only have 1 LED in them and a resistor.
I do need to change the turn indicator with a few diodes and added ground to work around the wiring between the left and right turn signal.
I think I will do this by adding in the diodes in headlamp connector wires.

His headlamp is powered by it's own rotor coil, so AC to a 35W or so headlamp, so I can thankfully ignore that for now and leave it for another
day.

Here are a few pics of my questionable work ;)
20220815_232531.jpg20220816_193450.jpg
 
So my modified with 7660 voltage doubler for 6V worked fine.
I did order some 6v LED bulbs, but need to wait 2 weeks or so for
'speedpak' from china. I got a pack of 10 of them for $17.

A few things - I like my modification with separate LED lights for each filament in a 1157.
For the tail brake/running light it gives a more distinct brighter difference, it's easier to
diagnose what is activated(running, brake). I do not know if they make them with separate LED
circuits per filament. If they did it would have avoided my need to add a diode for my
CM400T front running/turn issue. I will guess that if they do make them like this they are probably
a specialty item and would cost a fair amount more. The cheaper LED bulbs I have are fairly
easy to de-solder and re-purpose. I notice superbrightleds.com does sell 1156,1157 metal bases for 50 cents.

The blinker unit I am mostly happy with. It was about $7 each, two connector like OEM, it worked with
my 6V XL250S bike. I noticed I could pick up a set of 4 of these on Amazon for $12, so I'm a little bummed
I spent a whooping $7 each for these ;)
Some post I read mentioned they were not happy with the delay, where it is not on immediately
on when activated - does off cycle first. Older bi-metal can type would activate immediately(on)
and then cycle off. This blinker unit works with old high amperage filament or low amperage LED, works
at 6v or 12v, I like that. It has an potentiometer adjustment to change how fast it blinks.
I don't like the off-first cycle thing, but I'm not sure how big a deal it is. The post I read mentioned
safety concerns, but I'm not sure I have safety concerns as you should signal turn well before actual turn
anyway. My concern is more about immediate feedback that your turn signal is working, that would be preferred.
One side of my turn signal is flakey now, probably oxidation on switch from the old filament drawing lots of current,
and this is bigger problem with low current LED signals. But I can't blame the low current LED signals for this,
just need a cleaning.

Another thing to consider, but I don't think it applies to motorcycles, is the click that the old bi-metal type
give. Very noticeable in a car, I think it is a useful feature, but not noticeable on a motorcycle, as they are
so loud and blinker unit tucked away. And I do have a problem with forgetting to turn my turn signal off on the
motorcycle. It would be nice if this would turn off by itself, like they have arranged in a car. And I suppose
in a newer bike they probably have done this, but not on my 40 year old bike. Oh well.

I bought an extra blinker unit and have taken it apart to reverse engineer it. Preferably I would not have to
do this and they would provide schematics and such, but that is typically not the case. And I must say it is
a royal pain in the butt to do this sort of reverse engineering. Now this is fairly simple compared to say
Franks effort at the CDI, so Cudo's to Maraakete for doing that - it's a lot of work I can tell you that.
This has got 1 large mosfet and one more transistor, 2 medium sized caps and a bunch of resistors, fairly simple.
20220817_183752.jpg 20220820_201652.jpg
And for some totally unrelated news here is a pic of some great talent at a tournament in my local pool hall from all over the world.
20220817_202826.jpg
 
Last edited by a moderator:
Got my 6V LED lights from china, but they are too dim. Even when hooked to 12V they are still too dim. Strange but true. How do you screw up a LED light? Ask for 6V I guess. I was thinking they had a resistor in it that was maybe too big. I took one apart but there was no resistor used from 12v tip. Maybe there is a SMD resistors back of boards, but I don't want to try and take apart further. I did measure current, and it was drawing around 180ma at 8V, much more than my other 12V LED's, but still very dim. The LED's are a SMD module with 6 pins and unique looking, here is pic of the units from ebay listing. Don't get these ones, they are dim.
Dim_6v_lights.PNG
 
Last edited by a moderator:
I think those BA9 are the smaller indicator light form factor. For turn and brake I am used to 1156 as part number, this might be same as BA15S? But I don't have much luck searching on superbrightleds for 6V 1156. I would probably just try some different 1156 6V lights off ebay but stay away from anything that looks like what I got.
 
Back
Top Bottom