LED Brake, Park & Turn signal bulbs Caused electrical malfunction

[lal Naja]

I thought that I'd use LED bulbs in the front and back for Parking, Turn Signal and Brake. After I installed them I discovered that the simple swap caused the following problems.

When I used the turn signal all LED bulbs flashed as if I had used my emergency flash option. I also have a non LED center mounted brake light that flashed along with the License plate light and all instrument lights.

Some how the LED bulbs were feeding into the parking/instrument and brake light circuit. Totally weird! I was disappointed as I really like the brightness of the LED's. I re-installed the standard filament incandescent bulbs and everything functioned normally.

I had done a lot of research on how to do this. Purchased and installed a LED compatible turn signal flasher/hazard unit. Bought samples of five different LED bulbs and tested them all for visual appearance and brightness. To do this test I installed all the sample LED bulbs along with an incandescent bulb in Lucas light fixtures, mounted the lights on a wood board. Put the board on the wall in a dark room and triggered them from about 30 feet away. The LED's looked great and were brighter than the standard bulb.

I know that all the individual LED's that make up the bulb glow when in parking light mode and when the brake or flasher is applied the same individual LED's glow brighter. It's not like a double filament incandescent bulb that is two separate circuits and filaments.

Perhaps there is a different style LED bulb that I should be using that is designed for older style electrical systems.

If anyone could shed some light on what is needed to make them work correctly I would appreciate the support.

Thanks, Arthur

[emm427]

Did all 5 set do the same thing or the set you liked the best?

I have seen one defective bulb back feed the rest. When the customer applied the brakes all his parking lights came on. He had installed LED tail/brake lights. replaced them everything worked correct. try only the rear or front first to eliminate the problem area or bad bulbs...

[patrickt]

Originally Posted by lal Naja

If anyone could shed some light on what is needed to make them work correctly I would appreciate the support.

Put the LEDs in the rear only, and keep the "old fashioned" bulbs in the front. Your system may need the extra load that the old fashioned bulbs provide.

[lal Naja]

Originally Posted by emm427

Did all 5 set do the same thing or the set you liked the best?

I have seen one defective bulb back feed the rest. When the customer applied the brakes all his parking lights came on. He had installed LED tail/brake lights. replaced them everything worked correct. try only the rear or front first to eliminate the problem area or bad bulbs...

I had only bought one sample of each LED and tried them out. Then I purchased six of the one I liked best.

At this point I'm going to stick with the incandescent twin filament as everything is working just fine. At some time in the future when I have some spare time I may try to figure out the LED problem.

[Dangerous Doug]

Bob at ERA started a thread a while ago about some incandescent bulbs he'd tested for rear bulbs. I procured a pair and installed them on my 289 FIA. Nice and bright. I'll see if I can find the thread.

DD

[Dangerous Doug]

And here you go:

Bright bulbs for rectangular tail lights

[Hydramada]

lal Naja,

Patrick's suggestion of running the LEDs only in the rear is the simplest solution. If you want to run all LEDs then order one of these:

Metric Bike Diode Kit | Flashers & Load Resistors | Car Bulb Installation Supplies | LED Car Bulbs | Super Bright LEDs

This diode will stop the dash indicator from receiving feedback energy from the system as a result of the much lower power consumption of the LED bulbs.

[Dwight]

I have the electronic flasher but I had to run the "old fashioned" bulbs in the front to make everything work.
I did that four or five years ago. No problems.

Dwight

[lal Naja]

Originally Posted by Hydramada

lal Naja,

Patrick's suggestion of running the LEDs only in the rear is the simplest solution. If you want to run all LEDs then order one of these:

Metric Bike Diode Kit | Flashers & Load Resistors | Car Bulb Installation Supplies | LED Car Bulbs | Super Bright LEDs

This diode will stop the dash indicator from receiving feedback energy from the system as a result of the much lower power consumption of the LED bulbs.

Thanks for this....

I figured that my problem was that the internal design of the direct replacement LED's for 1157 style bulb is back feeding voltage from the flasher mode into the tail light mode and braking mode into the tail light mode and that Diodes would correct this. I do not have the knowledge on how to select suitable diodes to do this, so the info you've provided is most helpful.

[joyridin']

I did this on my Cobra, but I used a resistor instead of the electronic flasher. Mine works fine.

[csx4017]

This is the best description I have found. I will let you all decide for yourselves what your specific wiring should require. I know that on my car it is not as simple as screwing in an LED bulb....Cheers


MossMotors.com - Restoration Parts And Accessories For British Cars

[lal Naja]

In my pursuit of illumination I'm discovering that all Lucas light fixtures may not be created equally.

I have the four round Lucas lights on the back of my Cobra and although these look alike there is a subtle difference between them that was part of the problem that I encountered. And it may also be due, in part, that all LED's are not created equally too.

1157 conventional incandescent twin filament bulbs work in all four Lucas lights. And my LED bulb of choice only works in two of the Lucas lights. There is just enough difference between the angle of the two terminals in relationship to the bayonet pins/grooves and also the height of the brass terminals within light fixture resulting in a poor/no/intermittent contact.

I'm taking a close look to see if it is resolvable. PITA

Here are the two LED lights I picked. The large one has 102 Surface mounted diode's (SMD)and is white light. I installed these under the amber front park/turn signal light. The smaller has 48 SMD's and is red. Two are Stop/Tail lights and two are Turn Signal/Tail Lights. Brightness is amazing. Now to solve the issues.