Hi,
I would like to switch my turn signals to LEDs but only use 1 3 ohm resistor in the rear to minimize clutter and unnecessary wire modifications. It worked on my previous car and figured it would work on the Fiesta. When I temporarily wired the resistor in to test with the new LED bulbs, I got a hyperflash and I cannot figure out why. When I put my incandescent bulb back in the front, led in the rear and wired in 6 ohms of resistance on the rear led, it worked fine.
From digging on the internet:
Osram 3157A incandescent bulb = 27 watts
P = I * V, 27 watts = I * 12 volts, I = 2.25 amps; V = I * R, 12 volts = 2.25 amps * R, R = 5.33 ohms
Osram WY5W incandescent bulb = 5 watts
P = I * V, 5 watts = I * 12 volts, I = 0.42 amps; V = I * R, 12 volts = 0.42 amps * R, R = 28.8 ohms
Assuming that the turn signal circuit for each side, 2 3157 incandescent and 1 WY5W incandescent, is a parallel design, total resistance is 2.44 ohms
iBrightStar 3157 LED bulb = 4 watts
P = I * V, 4 watts = I * 12 volts, I = 0.33 amps; V = I * R, 12 volts = 0.33 amps * R, R = 36 ohms
Assuming that the turn signal circuit for each side, 1 3157 incadescent, 1 3157 LED, 1 WY5W incandescent and 1 6 ohm load resistor in the rear, is a parallel design, total resistance is 2.40 ohms
Assuming that the turn signal circuit for each side, 2 3157 LEDs and 1 WY5W incandescent with 1 3 ohm load resistor in the rear, is a parallel design, total resistance is 2.36 ohm
I would think being .08 ohms under OEM would be fine for the ECU to tolerate. The ECU tolerates the 2.40 ohms from the 1 LED circuit. Anyone have any insight as to why using 1 3 ohm load resistor in the rear wouldn't work? I can only think that the turn signals front and rear are on different circuits?
Also:
Auxito 194 LED bulb = 1.5 watts (from an amazon review)
P = I * V, 1.5 = I * 12, I = 0.13 A; V = I * R, 12 = 0.13 * R, R = 96 ohm
Assuming that the turn signal circuit for each side, 2 3157 LEDs and 1 WY5W LED with 1 3 ohm load resistor in the rear, is a parallel design, total resistance is 2.50 ohm. I haven't tried this yet.
I would like to switch my turn signals to LEDs but only use 1 3 ohm resistor in the rear to minimize clutter and unnecessary wire modifications. It worked on my previous car and figured it would work on the Fiesta. When I temporarily wired the resistor in to test with the new LED bulbs, I got a hyperflash and I cannot figure out why. When I put my incandescent bulb back in the front, led in the rear and wired in 6 ohms of resistance on the rear led, it worked fine.
From digging on the internet:
Osram 3157A incandescent bulb = 27 watts
P = I * V, 27 watts = I * 12 volts, I = 2.25 amps; V = I * R, 12 volts = 2.25 amps * R, R = 5.33 ohms
Osram WY5W incandescent bulb = 5 watts
P = I * V, 5 watts = I * 12 volts, I = 0.42 amps; V = I * R, 12 volts = 0.42 amps * R, R = 28.8 ohms
Assuming that the turn signal circuit for each side, 2 3157 incandescent and 1 WY5W incandescent, is a parallel design, total resistance is 2.44 ohms
iBrightStar 3157 LED bulb = 4 watts
P = I * V, 4 watts = I * 12 volts, I = 0.33 amps; V = I * R, 12 volts = 0.33 amps * R, R = 36 ohms
Assuming that the turn signal circuit for each side, 1 3157 incadescent, 1 3157 LED, 1 WY5W incandescent and 1 6 ohm load resistor in the rear, is a parallel design, total resistance is 2.40 ohms
Assuming that the turn signal circuit for each side, 2 3157 LEDs and 1 WY5W incandescent with 1 3 ohm load resistor in the rear, is a parallel design, total resistance is 2.36 ohm
I would think being .08 ohms under OEM would be fine for the ECU to tolerate. The ECU tolerates the 2.40 ohms from the 1 LED circuit. Anyone have any insight as to why using 1 3 ohm load resistor in the rear wouldn't work? I can only think that the turn signals front and rear are on different circuits?
Also:
Auxito 194 LED bulb = 1.5 watts (from an amazon review)
P = I * V, 1.5 = I * 12, I = 0.13 A; V = I * R, 12 = 0.13 * R, R = 96 ohm
Assuming that the turn signal circuit for each side, 2 3157 LEDs and 1 WY5W LED with 1 3 ohm load resistor in the rear, is a parallel design, total resistance is 2.50 ohm. I haven't tried this yet.