Rear blinkers too fast after changing lights

You have an electronic flasher that senses current flow to determine when a bulb is burned out. It flashes fast to alert you to that. LED bulbs draw very little current, and that makes it look to the flasher like bulbs are burned out. You need to add a resistor across each signal bulb to provide an additional path for current to flow to make up for what the LED bulbs aren't drawing. I haven't looked into this yet, but my guess is that resistor is going to be a pretty low value, as in one or two ohms. They will need to be high power resistors too; probably 15 or 20 watts.

As an alternative to the resistors, you can splice in a second socket for each signal circuit, and install a regular bulb that you can hide inside somewhere. Be aware though that regular bulbs get real hot so don't set them close to anything that could melt or burn.

Raymond Simon
September 12, 2015.

Thanks a lot. This means I can only go to an electrician like those car shops or I can do it myself?

I actually sell these LED lights at the nation's second largest old car show swap meet, but I never looked into adding resistors or light bulbs. I just know it is needed on a lot of cars. When you have the older two or three-terminal mechanical flashers, those can be replaced with similar-looking electronic flashers that are made specifically for what you're doing. As far as adding additional sockets and regular bulbs, I'd be willing to bet you'll find videos on You Tube from other people who have done this.

This is very basic electrical wiring that any mechanic should be able to handle, and it should be fairly easy for you to learn. The biggest issue with splicing in wires is to solder them, then seal the splices with heat-shrink tubing. "Scotch-Lok" connectors and similar products do not seal out moisture and will lead to corroded wires. A former student just spent over six hours on a vehicle with all kinds of electrical problems caused by someone installing a remote-start system with Scotch-Lok connectors under the dash.

You only need the resistors or light bulbs for the signal circuits. They're only needed with brake lights and tail lights if you have a "lamp-out" warning system and it's telling you those lamps aren't working.