Got a set of the below bulbs from summit racing but the won't work, I've heard that I might need some sort of resistor?

I thought that they were plug and play!


http://www.summitracing.com/parts/PL...n/?prefilter=1

Pilot Automotive LI-1157 - Pilot Automotive Light Bulbs

 

I'm not sure, but some of the M/C riders I know wire in a normal bulb under their seat and that makes them work. Not the skilled method of repair, but if you try a wired buld in line with them and they then work it might answer the resistance question.

 

Allot of times or most of the time those lights are plug and play in most 12volt setups across damn near every application but sometimes the resisters are needed you can get the resistors at any autozone, pepboys, ect i would try indiancreek's idea of a bulb inline from them to see for sure before you buy the resistors in my expierence they work but make your turn dignals blink too fast or can trigger a brake warning light on the dash those are the only times were i installed the resistors the fact that they are led means they use 1/8 the wattage and are much brighter in some setups with out the resistors wich is why people install them to begin with on a car this old they wont trigger the dash brake warning light to come on i have some in my tool box from a bunch of lights i used to install i will try it when i get home let you know if it works on my 79

 

LED's should work out of the box except for the turn signals. They don't generate enough resistance in the line to trigger the flasher. I installed a resistor in circuit for the turn signals on each side of my '70. Mounted mine in the front because it was easier to get at. Brake light circuit doesn't need a resistor.

 

buy a hevy duty flasher unit. that should take care of the problem.

 

thanks for the info

The lights do not come on at all, although havn't tried the flashers ( car has a heavy duty flasher )

I'll give the inline bulb a shot.

thanks

 

Maybe it's the Irish electricity! Too many O'hms.

 

many of the newer LED "bulbs" have the resistors built into the base of the bulb. i had no problem with hyper flash etc when i installed my led halo/led tails on my C5, but in adding full LED front corners, i had to install a hyperflash harness. when i added led bulbs to my 71 el camino a couple of years ago, i had to add some form of resistance into the circuit to get them to function properly. the light bulb trick is one of the easier ways to deal with it.

 

A typical 1157 bulb (dual contact turn signal bulb) pulls ~ 2 amps during the bright part of the blink/braking, and ~ .5 amps running as a tail light.
1156 (single contact tail light) draws ~ 2 amps.
Marker lights like 194's draw ~ .3 amps.

LED bulbs usually draw about 1/10 the current that their incandescent equivelant does.

To simulate the filament load on an LED bulb, you need to use ohms law to determine the resistance and required power rating of the resistor for each bulb circuit (where 1157's have two circuits):

E/I = R and (I)(E) = P

1157 turnsignal circuit shunt resistor calculation:
(I'm rounding down since the LED will draw some of the current)
resistance = 13.8 / 2 = about 6 ohms
power rating = 2 X 13.8 = about 25 Watts
Using this calculation, to simulate an incandescent bulb on an LED 1157 turnsignal circuit, you need a 6Ω 25W resistor.

As a general rule, just figure avout 25W per bulb in your selection of resistors.
The resistors are wired in parallel with the load, so these resistors are wired across the bulb in parallel with the filament.