I recently replaced every bulb on my EX500 with LEDs, and I put enough effort into it that I wanted to document it in case it helps anyone else with the same task. I’m sure that a lot of this information already exists on this site, but I haven’t found it all in one place, and I employed a custom solution for my turn signals.
I had two motivations in this, to increase light output and to lower the load on the electrical system. I also can’t stop at good enough, so I had to make sure that I changed EVERY, SINGLE, indicator or bulb to LED.
Front turn signals: Bulb type 1157, dual element, amber color. Found normal polarity on my bike (ground on outer conductor of bulb). Found that white LEDs are too white and too bright to keep a good amber color, so amber bulbs work much better.
Rear turn signals: Bulb type 1156, amber color. Found reverse polarity on my bike (positive on outer conductor of bulb), but previous owners hacked wiring harness. Found that white LEDs are too white and too bright to keep a good amber color, so amber bulbs work much better.
Tail lights/brake lights: Bulb type 1157, dual element, white color (red could also work). Found normal polarity on my bike (ground on outer conductor of bulb).
License plate light: Bulb type 1156, white color. Found normal polarity on my bike (ground on outer conductor of bulb).
Gauge cluster illumination: Bulb type 194, qty. 3, white color. Reversible socket, so polarity doesn’t matter.
Gauge cluster indicators (neutral, turn signals, oil, high beam): Bulb type 74 or T5, qty. 5, white color. Reversible socket, so polarity doesn’t matter.
Headlight: Bulb type H4 or 9003, dual element, white (6000k) color. Went for highest light output (12,000 lumen claimed) and LED placement to match incandescent filament location. Cut a vertical slit in lower part of rubber boot on back of headlight housing to clear the LED heatsink assembly. With the proper size cut the boot still fits snugly around the base of the bulb to create a weather resistant seal. Appears to work well, with a clearly defined cutoff line for low beam.
Flasher relay: Any cheap, generic, 2 wire LED flasher relay, typically labeled LS1-S-PIN. Plug and play, for the most part.
Turn signal resistors: 3.3kohm, 1/8watt, installed in parallel with the rear turn signal bulbs (one for each turn signal). These are NOT power resistors, but they are needed if ALL indicators are changed to LED due to the nature of how a 2 wire flasher relay must operate. Even the LED 2 wire flasher relay must drain some current when the lights are off, and if every indicator is an LED then this will cause problems with the front 1157 dual element bulbs in that they will be full brightness all the time, due to the drain current, and not flash. The 3.3kohm resistor allows about 4mA of drain current to bypass the LEDs when the flash is in the off state, which is enough for the flasher relay to operate properly. This only wastes about 50mW of power. This is 460 times LESS than the power consumed by one 23W incandescent 1156 bulb. These resistors could be installed at the front turn signals or the gauge cluster indicators, but I found the rear turn signals to have the easiest access.
The actual parts that I used:
I generally just searched Amazon and tried to select products with the correct LED placement and overall design (in my opinion).
Front turn signals:
Rear turn signals:
Tail lights/brake light:
License plate light:
Gauge cluster illumination:
Gauge cluster indicators (neutral, turn signals, oil, high beam):
Turn signal resistors:
I just had some laying around my house (actually measured 3.27kohm), but these would also work:
The resistors for the turn signals were fun to figure out. When I first installed the front turn signal LEDs I also did the rear and the flasher relay. This worked great and I was happy. Then I changed the gauge cluster indicators and the front signals would only glow solid bright when the turn signals were activated, not flash. At first I was confused, but I ordered a different style bulb for the front, just in case there was something weird about the particular bulbs I had, but sadly that was not the case.
After I hit a dead end with the bulb I started digging for a reference schematic for the flasher relay that I had. I finally found one that was probably similar, and I figured out the problem. The LED flasher relay still utilizes an RC time constant to set the frequency of the flash, but it uses its own internal discharge resistor instead or requiring the bulb load of typical flashers. The problem arises in that the EX500 uses a 2 wire flasher relay, hot and output to bulbs. For the oscillator in the flasher relay to work there must be a very small amount of drain current to allow the capacitor to charge during the off periods for the flashing. This current is so small that most LEDs would not illuminate noticeably, so it usually works. On the EX500 the front signals are dual filament bulbs that are always lit dimly, and it appears these type of LED chips will respond to very small currents if they are already partially illuminated, hence why they appeared to never flash. When they initially worked the gauge cluster still had incandescent indicator bulbs, so the drain current went through them, but changing to LEDs blocked that path.
I could have put a resistor right at the output of the flasher relay to ground, but that would have been wasting a tiny amount of power all of the time as the flasher relay always has power when the bike is running. By putting the resistors at the bulbs they only waste a tiny bit of power when the signals are on.
To determine the value of resistor to use I started at the reference schematic and looked at the internal discharge resistor, and it was about 2kohms. I know that the resistor that I install has no benefit being any smaller than the discharge resistor, so I knew to start looking at around 2k. I selected a 10kohm potentiometer to use for testing, but I didn’t want it to ever short the flasher to ground, so I also put a static 1kohm resistor in series. I then used a sharp multimeter probe to pierce the insulation of the flasher wire while it was on and connected my test resistor setup between that wire and ground. I proceeded to adjust the potentiometer until I found the value at which going any lower doesn’t yield any noticeable difference in how far “off” the LED is when in the “off” flash. The measured value was about 4.8kohm, but this was the limit, so I wanted to apply a safety margin and go a bit lower, so I selected 3.3kohm. This yields only 4.2mA of current at 14VDC, or 59.4mW of power, which I found acceptable. I installed the permanent resistors inside of the rear turn signal housings, and they work perfectly.
If there is any more info that I could provide that may be useful, let me know and I’ll try to update this post.